Green Arrow, The Flash and Supergirl travel to the Gotham City of Earth 1 in search of the mysterious man at the heart of Cisco' vibe vision. It is here they meet Kate Kane, who points them in the direction of Dr. John Deegan - an Arkham Asylum psychiatrist with a bad reputation, even for Gotham.
The body-swap genre of comedy, particularly the 1976 Freaky Friday film, the television series Quantum Leap (Curtis and Cisco references it while wondering exactly how the body swap worked), Crisis on Infinite Earths (the red skies and yellow lightning, the Monitor's reference to a being that will destroy all reality and his need to find heroes to fight it), Neil Gaiman's Sandman (the Book of Destiny), the Batwoman comics of J.H. Williams and Greg Rucka, the post-Crisis Batman comics where Batman was viewed as an urban legend and every Batman story featuring a break-out at Arkham Asylum.
Barry says that if his and Oliver's body-swap were like Quantum Leap he would only look like himself in the mirror. On Quantum Leap, the body-swapping time-travelers saw the person whose body they leaped into when they looked into a mirror, while the audience saw the actor dressed as the person whose body they leaped into.
Oswald Cobbleepot is shown to have a cell in Arkham Asylum. In most versions of the Batman mythology, The Penguin is usually sent to Blackgate Penitentiary as he is not technically insane.
Ruby Rose gives an amazing first performance as Kate Kane. Her chemistry with Melissa Benoist is particularly notable.
The fight between Flash and Green Arrow as they are strung out on Scarecrow gas is amazing
The episode opens with a special opening sequence, starring Grant Gustin as Oliver Queen, based around the altered reality of Elseworlds. Strangely enough, it reflects the changes to the show as of the Arrow Season 7 mid-season finale, and shows Grant Gustin and Emily Bett Rickards kissing as well as Katie Cassidy showing a picture of a bruised Grant Gustin in court.
Oliver Queen believes that Batman isn't real and the result of a conspiracy theory promoted by the Gotham City Police Department to scare criminals. This was the reality of the Gotham City in the post-Crisis Batman comics, where Bruce Wayne and most of Gotham's vigilantes kept a low profile and were considered by the public at large to be urban legends. How this explained the Batman's presence in the Justice League at the same time was largely hand-waved depending on the writer.
Oliver Queen claims to be the original vigilante, while arguing with Barry about the existence of Batman. In the reality of post-Crisis DC Comics, Oliver Queen did start operating as Green Arrow just before Bruce Wayne started his career as Batman. He also adopted Roy Harper and brought him into action as Speedy before Dick Grayson became Robin.
Upon arrival in Gotham, Ollie suggests contacting a radio personality named Vesper Fairchild, who he says knows everyone in Gotham. In the original Batman comics, Vesper Fairchild was a radio show host who was briefly linked to Bruce Wayne romantically. She first appeared in Batman #540 in March 1997. She was later killed by the assassin David Cain as part of a plot to frame Bruce Wayne for her murder. This kicked off the Bruce Wayne: Murderer? and Bruce Wayne: Fugitive storylines that ran through the Batman comics in 2002.
The street corner where Kara, Barry and Oliver are arrested is said to be Nolan and Burton. This is a nod to Tim Burton and Christopher Nolan - the two directors whose Batman films are most widely popular with the general public.
The modern version of Katherine "Kate" Kane first appeared in 52 #7 (August 2006). Bruce Wayne's first cousin on his mother's side, Kate was part of the Kanes of Gotham - one of the city's five founding families. Following in her father's footsteps to enlist in the Army, she resigned her commission at West Point rather than lie about her relationship with another female cadet in violation of the honor code of the time. Kate drifted through life without direction for a time, another idle rich heiress, until an attempted mugging. When Batman came to her rescue only to discover the heiress had easily subdued her assailant herself, Kate became inspired to become a vigilante herself. She spent the next two years training, eventually taking the Batwoman mantle independent of Batman. It was only later that the two cousins discovered one another's identities.
We know little about the Arrowverse version of Kate Kane beyond her being Bruce Wayne's cousin and being Batwoman as of this episode.
The WiFi password in Wayne Enterprises' offices is Alfred - a nod to Alfred Pennyworth, Bruce Waynes butler.
Kara finds a bust of William Shakespeare in Bruce Wayne's office. In the 1966 Batman show, the trigger for the hidden passage to the Batcave in Bruce Wayne's study was hidden within a bust of William Shakespeare.
We see a number of cells in the halls of Arkham that hint at famous Batman villains. These include The Penguin, Poison Ivy, Clayface and The Riddler. There is also a cell for "Guggenheim, M." - a nod to Arrow writer, producer and show-runner Marc Guggenheim.
One of the inmates seen escaping Arkham Asylym wears a featureless gold mask. This is a reference to The Psycho Pirate - a JSA villain with the power to manipulate the emotions of others. He became a figure of some prominence after Crisis on Infinite Earths, being only one of a handful of beings who remembered the existence of the multiverse. The Psycho Pirate primarily operated out of Gotham City and famously ruled the city by using his powers to take control of Bruce Wayne and Alan Scott. (The secret identities of Batman and Green Lantern.)
The storage room at Arkham Asylum contains a mask resembling that worn by Tom Hardy as Bane in the movie The Dark Knight Rises.
Caitlin encounters a woman digging through a storage room in Arkham Asylum, looking for something to make her cold. This is Nora Fries - the wife of Victor Fries - who was cryogenically frozen while her husband tried to find a cure for her condition. Apparently, on Earth 1, she was kept at Arkham, presumably so he could work on her while serving his sentence. She eventually assembles an ice gun, her husband's weapon, which she uses to fight Killer Frost.
Nora Fries is played by actress Cassandra Jean, who is the wife of Arrow star Stephen Amell.
Oliver accidentally breaks a box containing several gas samples belonging to a J. Crane. This is a reference to Jonathan Crane, a.k.a. The Scarecrow and the gas turns out to be his famous fear gas.
Batwoman says "World's Finest" when Supergirl suggests they might be a good team. This is a nod to the classic comics series World's Finest, which was based around Superman/Batman team-up stories.
The Barry Allen who finally breaches into ARGUS HQ identifies himself as The Flash of Earth-90. He is played by John Wesley Shipp, who also plays Dr. Henry Allen and Jay Garrick on The Flash. In the year 1990, John Wesley Shipp played Barry Allen on a short-lived CBS series based on The Flash comics.
When The Flash of Earth-90 sees John Diggle, he asks him where his ring is. This is a nod to a long-running fan theory that John Diggle's middle name would be revealed as Stewart and he would eventually become the Green Lantern as a tribute to John Stewart from the Green Lantern comics. Apparently the Earth-90 version of John Diggle is a Green Lantern.
The Flash of Earth-90 identifies the artifact The Monitor gave Dr. John Deegan as The Book Of Destiny. This seems to be a nod to The Book of Souls - a book guarded by Destiny of The Endless, which can be used to alter reality.
Everything The Flash of Earth-90 says about The Monitor's plans is taken directly from Crisis on Infinite Earths.
In the new reality created by Dr. Deegan, Oliver and Barry are now a duo of bank robbers called The Twigger Twins. In DC Comics, there were two separate pairs of twins who were robbers called The Trigger Twins. The first were named Walt and Wayne Trigger and they lived in the Old West, first appearing in All Star Western #58 in May 1951. The second pair were Tom and Tad Trigger and they first appeared in Detective Comics #667 in October 1993.
Curtis says they need a pattern recognition algorithm to interpret the meaning of the red skies and strange storms. This means they need to bring in Felicity.
Curits says that the quantum amplitude of the energy discharge of the lighting storms is consistent with that of a dimensional breach.
Cisco says the energy discharges of the lighting storms are not tied to The Speed Force.
Felicity theorizes that if the lighting strikes are attempted dimensional breaches, there might be a way to stabilize the quantum flux to allow whatever is trying to get through to get through. This leads to Felicity designing a quantum flux anchor.
Felicity is using a quantum flux anchor that utilizes wave theory to fire nano-particulates across an Einstein-Rosen bridgeto create a secure claxon field. (Or, as Caitlin puts it, it's a big magnet that will draw whoever is trying to breach through reality to them.)
Cisco detects multiple quantum surges as the quantum flux anchor is activated.
When Kara tries to sneak Caitlin into Arkham Asylum as a patient, she describes her condition as persistent sub-thermal homeostasis with involuntary gelid substantiation. (i.e. she gets cold and freezes stuff.)
Nora Fries says her cryostasis unit shut off along with the locks on the asylum cell doors.
Nora Fries says her condition requires she be kept at 196 degrees below zero.
The Book of Destiny has a cryptographic lock on it. The lock is also metaphysical in nature.
Oliver Queen: My name is Oliver Queen. After six months in Hell, I have been released from prison with only one goal - to save my city. But things have changed. Instead of operating outside the law, I am now working alongside the police. I am no longer Inmate 4587. I am once more The Green Arrow.
(John Diggle sees Green Arrow, Supergirl and The Flash.)
John: Son of a bitch!
Supergirl: Is that any way to greet your friends?
John: All I know is that whenever the three of you show up, it usually means we have one big problem.
Diggle: An immortal Egyptian. Aliens. Parallel Earth Nazis. I have no idea why I'm even surprised at this point.
Curtis: I'm still trying to figure out if this is more like Freaky Friday or Quantum Leap.
Barry: No. If this were like Quantum Leap, I'd only look like myself in the mirror.
Curtis: Yep. You are definitely not Oliver Queen.
(The trio are trying to find the radio station where Vesper Fairchild is employed.)
Barry: I'm surprised they put it in the bad part of town.
Kara: It's cute how you think there's a good part of this town.
(Kate Kane has just told "Ollie" that if he's come to Gotham to compete with Batman, he's wasting his time.)
Barry: I would never compare myself to a total badass like Batman.
(Oliver is glaring daggers at Barry this whole time.)
Kara: Uh - I what I think Oliver is trying to say is thank you for getting us out of jail.
Oliver: What Oliver's actually trying to say is who are you and why are you helping us?
Kate: Gotham has enough problem without a guy in green leather showing off his arrows to everyone. So the faster you find what you're looking for, the faster you can get the hell out of my city.
Felicity: My marriage with Oliver is strained by the fact that we've become different people. (quietly) Quite literally in Oliver's case.
(Ollie reveals he stole a data drive from GCPD HQ.)
Barry: You stole data from the police?
Ollie: No! No, The Flash did it.
(Ollie walks off as Barry is aghast. Kara discretely covers her mouth with her hand.)
Barry: It's not funny.
Kara: I'm not laughing!
(Kara is clearly trying hard not to laugh but is losing the battle.)
(Caitlin is trying to explain to Felicity why Oliver would hide the body-swap from her.)
Caitlin: When he and Barry tried to tell us what was going on with them, weeeeeeee... knocked them unconcious and locked them in The Pipeline.
Caitlin: (sheepishly) Wasn't our finest moment. But I'm sure that that's the reason Oliver didn't want to take any chances with you.
Felicity: I appreciate you saying that... but it's just another excuse in a long list of excuses for Oliver's behavior.
Caitlin: Oliver does love you, Felicity.
Felicity: Yeah? Well, what's love without respect? Or trust?
Caitlin: I don't know. But as long as there is love, you can't give up on it. That's the one thing I do know. After everything I've been through. Everything I've suffered.
Felicity: ... thank you.
(Kara asks Kate if Bruce might have gone crazy trying to keep his private life out of the public eye.)
Kate: Sitting at that desk? Staring out that window? Watching the city we grew up in rot at its core?You find a way to not break. Bruce didn't leave Gotham without a fight.
Kara: You know, I've got to say - all the corporate billionaires I know wear Versace and have 500 fewer tattoos.
Kate: (flirtatious) And those are the ones you can see.
Batwoman: I don't do tearful goodbyes.
Supergirl: No, I - I just wanted to wish you luck. Wherever your cousin is, I'm sure he's really proud of you. (points to her eyes) X-Ray vision. You really do have a lot of tattoos.
Batwoman: And somehow I feel like Kara Danvers doesn't have a single one.
Supergirl: You know, it's such a shame I have to go. Because I feel like we would make a good team.
Batwoman: World's Finest.
(Batwoman offers Supergirl he hand. They shake.)
Oliver: People change, Felicity. It means we're growing. It means we're evolving. Except for one thing. One thing that will not change... is how I feel about you. Love is too small a word. And no matter who you are, or what you become - no matter who I am, or what I become... you will always be... you will always be the love of my life. People change. That never will.
(The Flash of Earth-90 suddenly appears in the middle of ARGUS HQ.)
Barry: Oh my God, Dad?!
Flash-90: My name is Barry Allen. (Looking to Diggle) Hi, John.
John: Do I know you?
Flash-90: (confused) You're not wearing your ring. Things must be different here.
Oliver: He said you were testing us!
Monitor: And thus far I am unimpressed. A crisis is imminent. Someone is coming. Someone far, far more powerful than myself. I mean to prepare.
Barry: By giving a nut-bar an all-powerful reality-rewriting book?
Monitor: I am testing universes to find one, I hope, strong enough to stand against him.
As the episode opens, the skies above Star City have turned red and random bolts of yellow lightning are striking everywhere. One of them nearly hits Curtis Holt in his ARGUS Comms van.
Kane Wolfman, last seen in A606, returns. He is wearing armor in imitation of his father's Deathstroke costume, only without a mask. He is wanted for 19 violations of international law. He is stopped by Supergirl, Green Arrow and The Flash.
John Diggle refers to the previous three years Arrowverse crossover events, describing Vandal Savage (an immortal Egyptian), the Dominator Invasion (aliens) and Crisis on Earth-X (Parallel Earth Nazis.)
Oliver decides not to tell Felicity about the body-swap since they are having enough troubles without him throwing one more thing at her.
According to Oliver Queen, Batman is an urban legend created by the Gotham City Police Department to scare criminals.
Barry Allen believes that Batman is real.
Ollie suggests seeking out Vesper Fairchild - a radio personality he once spoke to regarding a story on white collar crime that she was investigating. He thinks he might have slept with her while trying to convince her Queen Consolidated was on the up-and-up. It is later confirmed by Barry that Ollie did sleep with her back in his drunken playboy days.
Barry tells Kara about how Oliver once slept with his girlfriend's sister. (i.e. Sara Lance.)
The rooftop of the Gotham City Police Department does have a Bat-Signal, under a dusty tarp.
Oliver Queen is recognized by the Gotham City Police Department, prompting them to call for back-up.
According to Cisco, the red skies and lightning are following Barry and Oliver.
Caitlin accidentally reveals the body swap to Felicity.
When Oliver, Barry and Kara are arrested, Oliver calls Black Siren for assistance in getting out of prison. She elects to let them spend a night in jail.
Kara refers to Barry and Ollie taking on each other's personalities in F509.
Oliver steals a drive containing the GCPD database before he leaves the jail.
Kara,Oliver and Barry are taken to the Wayne Enterprises building to meet the person who bailed them out. She is revealed as Kate Kane.
Bruce Wayne left Gotham three years earlier. Nobody knows why or where he went.
According to Oliver, Wayne Enterprises sank after Bruce Wayne disappeared and his board of directors went to town with a bunch of get-rich-quick scenes.
Bruce Wayne is said to have left Gotham shortly after Batman disappeared. Many people left Gotham after Batman's disappearance, according to Kate.
According to Kate Kane, Gotham City became even worse after Batman left town and it took a toll on Bruce.
The WiFi password for Wayne Enterprises's suite is Alfred.
Caitlin tells Felicity about why Oliver probably kept his body-swap a secret.
Oliver is fairly competent with a computer. He is finally able to run a facial recognition program to identify his sketch as Dr. John Deegan.
Dr. John Deegan has a record for illegal experimentation and torture, having conducted experiments on his patients. He was acquitted on all charges due to technicalities that led to the charges being dropped. He was still fired and suspended from the medical board for two years, but that occurred five years ago.
Kate reveals that Bruce Wayne is her cousin to Kara.
Kate is in the process of turning the Wayne Enterprises building into a real estate development firm.
Kara reveals that her cousin is a friend of Bruce Wayne's. She then changes this to frienemy.
Kate knows Dr. John Deegan and says he is a doctor at Arkham Asylum.
When the quantum flux anchor is activated, Caitlin thinks The Flash of Earth-90 is Jay Garrick. He tries to tell them that they need "the book" to fix things.
Oliver and Diggle enter Arkham Asylum as themselves, claiming to be part of an ARGUS/CCPD/GCPD operation.
Kara and Caitlin sneak into Arkham Asylum, with Kara posing as a medical worker and Caitlin a potential patient.
Dr. Deegan reveals that he was trying to make himself into The Flash when he accidentally switched Barry and Oliver.
Kara recovers the book from Dr. John Deegan.
After being exposed to Scarecrow gas, Oliver's hallucinates Malcolm Merlyn returned from the dead. Barry hallucinates The Reverse Flash.
The Flash of Earth-90 reveals the alien to be a being named Mar Novu, who now calls himself the Monitor. He has been releasing the Book of Destiny on various realities as a means of testing them in anticipation of a great Crisis He believes the "Elseworlds" created by The Book Of Destiny can act as simulations of the collisions of realities that are coming.
The Monitor reveals that the heroes of Earth 1 and Kara are the first group to sucessful retrieve the Book of Destiny from the person to whom he presented the book.
The Monitor takes the book from ARGUS and gives it back to John Deegan, telling him to think bigger.
Reality is rewritten a second time, with Oliver and Barry now being a powerless duo of bank robbers. It is unclear what happened to Kara.
Malcolm Merlyn, Kane Wolfman and Ricardo Diaz are Central City cops in the new reality.
The episode ends with a black-suited Superman capturing Barry and Ollie.
We don't learn anything about Kate Kane's background or training or how long she's been a vigilante.
The Fridge Factor
Good news - we get a scene between Caitlin and Felicity - the two most prominent scientists in the Arrowverse! Bad news - they're discussing Oliver and Felicity's relationship, so it falls the Bechdel test.
The Bottom Line
A lot more fun than one usually expects from an episode of Arrow. There's a few oddities here and there (Nora Fries' presence is largely unexplained and serves mostly as an Easter Egg for the few fans who will get who she is) but it's largely satisfying, if somewhat senseless, given how quickly The Monitor undoes everything our heroes have done and dismisses them even while admitting they've done the best of anyone he's tested so far. Still, for a big, dumb action-packed comic book storyline, it's perfectly captures the spirit of its source material.