Barry Allen and Oliver Queen wake up in one another's bodies, with everyone in the world seeing them as the other man. The good news is that a trip to Earth-38 confirms they aren't crazy, as Kara sees them for who they really are. Unfortunately, that leaves Central City without its greatest hero as a robot that can copy metahuman abilities goes on a rampage.
The body-swap genre of comedy, particularly the 1976 Freaky Friday film, the television series Quantum Leap (Barry references it while wondering exactly how the body swap worked), the television series Smallville (theme music and imagery as we see Smallville, Kansas on Earth-38), the Adventures of Superman show (nod to the "strange visitor from another planet" introduction"), Superman: The Movie (Clark's responding "a friend", when Cisco asks who he is) and every Justice League comic depicting the League fighting Amazo.
Ollie says he woke up in bed with Iris. when she was already cooking breakfast when he woke up. (He lies to get Barry to start taking the situation seriously since the idea of another man waking up with Iris is the first thing that upsets him about the body swap.)
The Bunker is up and running in Star City, when it was in ruins the last time we saw it on Arrow. (Presumably it was repaired as part of whatever Dr. John Deegan did to rewrite reality to switch Barry and Ollie's places?)
Why does Barry try and tell Ollie what phrase to say to his wife to convince her he's the real Barry Allen rather than telling her something only the real Barry Allen would know as Oliver Queen?
Where did Barry get the materials to make remote control crossbows in Smallville?
Why are Clark, Lois and Kara so indifferent to Ollie being shot in the back with two arrows?
Elizabeth Tulloch nails Lois Lane out of the gate. Hopefully we'll get to see more of her on Supergirl in the future.
It must be said that Grant Gustin and Stephen Amell do a great job playing off of each other and trying to play each other over the course of the episode.
The effects-work for the fight between our heroes and Amazo sets a new standard for the show.
The Elseworlds logo for the crossover event is the same as the logo for DC Comics Elseworlds imprint.
Dr. John Deegan is an original character created for the Arrowverse. His name is similar to that of Dr. John Dee - the secret identity of the Justice League villain Dr. Destiny, who had similar powers to alter reality and influence the dreams of other people.
The book Dr. John Deegan acquires is not identified by name, but resembles The Book of Souls - an artifact belonging to Destiny of The Endless. The symbol of everything that will ever happen across the whole of time, The Book of Souls can potentially be used to rewrite reality. It is the purpose of Destiny of the Endless to prevent this from happening and to keep reading the book so as to determine what is happening at any given time.
Though not identified by name in this episode, the alien who gives the book to Dr. John Deegan is easily identified by comic book fans as a Monitor. First appearing in New Teen Titans #21 (July 1982), there was originally a single Monitor, who was an avatar for the whole of the positive-matter multiverse. This Monitor became a major figure in Crisis on Infinite Earths in 1986, where it united the heroes of multiple realities against an Anti-Monitor who wished to destroy all matter. This resulted in a single DC Universe from 1986-2005. When the multiverse was restored in Infinite Crisis in 2005, a whole host of Monitors were created with each Monitor representing a single Earth. These Monitors joined together to prevent the interactions of beings from different realities, in order to prevent future "crisis events" that could unmake the whole of the multiverse.
As the episode opens, the skies are turning red and lighting is filling the skies. This is a nod to the odd weather that arose during Crisis on Infinite Earths.
Barry makes reference to the film Freaky Friday, in which a mother and daughter trade bodies and come to appreciate how difficult one another's lives are. Barry is quick to note, however, that this is not an accurate comparison to what has happened to him and Oliver. Both men still look precisely as they did before but Oliver Queen is now addressed as Barry Allen and vice versa.
Barry also makes reference to the television series Quantum Leap - a science fiction series about a time-traveler who traded minds with a series of people across time. He asks to see a mirror in reference to how the hero of the show saw the face of the person whose body he possessed whenever he looked in a mirror, appearing to be his true self to the audience at home. Again, this isn't a wholly accurate analogy for how the body swamp in this episode worked.
The episode opens with Oliver having to stop a robbery at Ivo Labs. This is a reference to the character of Professor Anthony Ivo - a mad scientist with a fear of death whose search for immortality brought him into conflict with the Justice League. Professor Ivo first appeared in The Brave and The Bold #30 in June 1960. It was here that he built the first Amazo robot and used it to steal the powers of the Justice League so it would be powerful enough to abduct various long-lived creatures as part of Ivo's efforts to brew an immortality elixir.
Professor Ivo previously appeared in the Arrowverse, being the chief villain in the flashbacks during the second season of Arrow. This version of Ivo owned a ship called the Amazo, on which he conducted horrible medical experiments while searching the sea around Lian Yu for a sunken Japanese submarine containing the miracle drug called Mirakuru. It was implied that this Professor Ivo was seeking Mirakuru as a cure for his wife, Jessica, who was dying of some kind of degenerative disease that was causing her to lose her memory. He was eventually killed by Oliver Queen.
The Arrowverse version of Amazo is said to have been commissioned by ARGUS to create a technology capable of analyzing metahumans in the field and formulating a response to them. It functions through the use of a unique nano-adaptive hybrid of the Mirakuru serum, which once transformed Slade Wilson into Deathstroke.
It is unknown if the presence of Ivo Labs here is meant to indicate that Professor Ivo is alive due to alterations of the timeline or that his company might have gone on without him.
As we first see the Smallville of Earth-38, the song "Save Me" by Remy Zero plays. This was the theme-song of the television series Smallville.
The first shot we see of Smallville, Kansas from the air is also identical to the first shot of Smallville's opening credits.
Clark refers to himself and Lois as "strange visitors" when talking about their trip to Argo City. This is a nod to the introduction of the original Adventures of Superman show, which described Superman as a "strange visitor from another planet."
Ivo Labs is located on the corner of Waid and Augustyn Streets in Central City. This is a tribute to writer/editor Mark Waid and writer/editor Brian Augustyn. Both are notable for their work on The Flash comic book as both writers and editors. The two also co-wrote two separate runs on The Flash together. Perhaps more importantly, given the presence of a Justice League of sorts in this episode teaming up to fight Amazo, both writers also worked together on JLA: Year One - a mini-series widely regarded as the best Justice League origin story ever written.
Whenever the Amazo robot duplicates a person's powers, their emblem from the comics briefly appears on the robot's chest.This occurs even for those heroes like Killer Frost and Elongated Man who don't have distinctive symbols in the Arrowverse.
At one point, Ralph notes that despite strange things happening it isn't even Tuesday. This is a nod to how The Flash usually airs on Tuesday nights and, given the way the show is dated in real time, most of the major events of the show take place on Tuesdays. It also notes how this episode first aired on a Sunday evening.
The "Who are you?"/"A friend." exchange between Cisco and Clark is a nod to Superman: The Movie, where Lois Lane asks Superman the same question the first time he saves her life and he gives the same answer.
Dr. John Deegan has a theory that eugenic insights can be used to make everyone "super."
Diamonds can be used as conductors.
Caitlin is unable to detect any anomalies to Oliver Queen's body or mind.
Barry's brain-scan is normal, showing no signs of hypnosis or psychic interference.
Cisco does not detect any tachyons in Barry's body. This shows that nobody is interfering with the timeline.
The cells in STAR Labs secret pipeline prison are Tesla conductor tubes that dampens meta-powers.
650 nanometers is the wave-length for red light. Cisco is unable to call ARGUS because of interference on this wavelength..
Oliver tells Barry that he can dislocate his thumb without breaking his hand because, in this reality, he was trained in the art of escapology by Anatoly Knyazev, stretching and conditioning his ligaments.
Phasing is when a speedster vibrates at the frequency of air, causing the cells in the body to become so excited that they can pass through solid matter.
AMAZO is an anagram for Anti-Meta-human Adaptive Zootomic Organism.It replicates metahuman abilities through the use of a nano-adaptivie hybrid of the Mirakuru serum. It scans metahumans and then uses this hybrid formula to replicate those abilities.
(A Caption Box reads Earth-90 as we see the aftermath of a war and numerous people in costumes lying on the ground, dead. Eventually we come to a figure in a somewhat familiar red suit crawling on the ground toward a large book that is glowing purple. A figure walks over and picks the book up before he can reach it.)
The Monitor: You failed.
(The figure in red pulls himself up to his knees. It is The Flash. Not the Flash we know, but definitely The Flash.)
The Flash: (gasping) Why are you doing this?
The Monitor: You did this to yourselves. And now... all of you will perish.
(The Monitor opens the book and light pours from it. As he does so, The Flash stands and runs toward the camera, as a familiar theme to older comic book TV show fans plays, as we zoom in on his chest symbol....)
(Oliver Queen has just unleashed the ring from Barry Allen's ring and reflexively changed into his costume. He looks down at himself in shock.)
Oliver: Oh, Barry... what have you done this time?
(Oliver stares down a thief.)
Oliver: (growling) You have failed this city.
Cisco: (over the comms) Pretty sure that's not your line.
(Barry reflexively spars with John Diggle, knocking him down.)
Barry: I'm Oliver Queen.
John: (still on the ground) Yeah, I'll say.
Barry Allen: I'm the Green Arrow! (face falls) Holy crap.
(John Diggle hands Barry Allen the Green Arrow costume.)
John: Suit up.
(Diggle walks off as Barry looks at the green leather, dumbfounded.)
Barry: How do I put this... I forget do I need help putting this on?
Barry: You gotta admit this is a little cool!
Oliver: I will find it a lot cooler when I wake up in my own bed tomorrow morning.
(There is a long pause as this implication sinks in to Barry.)
Barry: You woke up in bed with Iris?
Barry: We have to fix this right now!
(Oliver joins Iris on the STAR Labs balcony to have a private chat.)
Ollie: (taking a glass of wine) This should help.
(Iris bites her lip.)
Iris: I guess you forgot you can't get drunk?
Ollie: (sighs) This day could not get any worse.
Oliver: Why are we in your secret prison?
Barry: It's not a prison. It's a Tesla conductor tube that dampens meta-powers. (pauses) Okay, it's a prison.
Oliver: I spent the past seven months in a maximum security prison. And no matter how bad things got - and they got bad - every cell had a toilet!
(Barry, annoyed at Oliver's complaining, kicks the wall. A panel opens and a steel toilet bowl slides out of the wall.)
Barry: You sure you can't hold it?
(Oliver gives Barry a long-suffering look indicating that's not why he wanted it.)
Barry: Oh! You want to back-up the pipes-
Ollie: And fry the dampener, yes.
(We see Clark Kent lifting up the front end of a truck as Lois Lane is under it, in front of a barn. Kara Danvers is in the background, busying herself with something else.)
Lois: I'm writing it!
Clark: We've been over this, hon.
Lois: No, you talked, I ignored. (handing Clark a car part) You need a new muffler.
Clark: I think this is a tie rod end.
Lois: Come on, Kara, back me up here!
(Clark lowers the truck.)
Kara: Uh, no, thanks. I know better than to get involved in a debate with Lois Lane.
Lois: But you do know the feeling - that itch, that fire in the back of your head, the siren song of a story that has to be written?
(Clark shakes his head and gives Kara a pleading look behind Lois' back as Lois smiles at Kara knowingly.)
Kara: Yeah, I do, I do.
(Lois spins around and smiles at Clark triumphantly.)
Clark: The world is gonna want to know why Lois Lane went to Argo City with Superman.
Lois: Details! I'll make up a reason.
Clark: Oh, so much for truth in journalism.
Lois: Says the reporter who writes about his own exploits as Superman.
(Clark drops his head in acknowledgement, admitting defeat.)
Lois: I was the first human to set foot on what's left of Krypton, to lay eyes on the Jewel Mountains, (rolling her eyes) to endure the endless, torturous deliberations of the High Council, and I have to write about it. One small step for Lois Lane. One giant leap for Lois Lane's career!
Clark: Says the woman who is already the most famous, feared, and intrepid reporter on two planets.
Lois: And yet (walking over to Clark and taking the glasses off his face) someone on this farm is still making... 21 cents on the dollar more than me.
(Lois replaces the glasses on Clark's face.)
Lois: And it ain't Kara, honey.
(Lois grins cutely and leans up to kiss Clark.)
Kara: I've never been challenged like that before, just to my face: "Tell us who you are, Supergirl." Well, except for Ms. Grant.
Clark: Well, I'm sure it was harder when it's the President doing the threatening.
(They both pause a moment to consider this.)
Kara: Cat was scarier.
(They both laugh.)
(Oliver and Barry are training each other on the Kent farm.)
Barry: You know what? Why don't you go over there, run at me, and I'll try and hit you with an arrow?
Ollie: Right, okay. (pauses) Where did you bury the remote control bows?
Barry: Dude! Come on, I'm not you.
Ollie: Yeah, well, okay.
(Ollie runs off into the distance at super-speed.)
Barry: (quietly) Here we go.
(Oliver runs forward, easily catching the arrow Barry shot at him.)
Ollie: Nice try.
(Two remote control bows rise up from the ground and shoot Oliver in the back.)
Barry: (laughing) Oh, I've been waiting four years for that, man!
(Cisco runs through his theory on how the strange weather, Barry and Ollie trading places and his vibe of the strange alien are all connected.)Ralph: Man - it's not even Tuesday.
Cisco: (To Clark) Who are you?
Clark: A friend.
(Clark opens up his shirt to reveal his Superman uniform.)
The Monitor: Fascinating. I wouldn't have thought the men of this Earth had this capacity. But it won't avail you. None of you can stop what's been set into motion. You're best off giving up now, because nothing you can do can alter what's about to happen.
The episode opens with an abbreviated version of the scene set on Earth-90 that first appeared at the end of S408.
Oliver Queen wakes up in Barry Allen's apartment as Iris West is cooking breakfast.
Iris refers to the most recent battle with Cicada and the discovery that Killer Frost is immune to his powers from F508.
Oliver stops a robbery at Ivo Labs.
Both Oliver and Barry seem to have some kind of adaptive muscle memory regarding the use of their abilities but no knowledge regarding them.Oliver is able to reflexively throw lightning, but needs instruction on how to accomplish a task that requires fine control like phasing. Likewise, Barry is able to make amazing trick shots and reflexively out-fights John Diggle in a hand-to-hand fight, but lacks Oliver's natural battlefield wariness.
Oliver's attempt to throw lightning at Ivo Labs activates a robot that had been kept in a crate that the lightning broke open.
Cisco refers to his break-up with Gypsy from late last season as Oliver tries to shrug out of Iris's public display of affection.
Barry now has scars on his body he didn't have as The Flash.
John Diggle asks for Barry's help in dealing with the Bratva and the Bertinellis fighting over an old Ricardo Diaz weapon cache in The Glades.
The running gag in which Diggle throws up after being made to move at super-speed continues.
Iris says that Felicity called her while Oliver was in prison and told her about how Ollie cut a deal with the FBI to go to prison without talking to Felicity first.
Iris uses some of Ray Palmer's nanites to dope up Oliver.
Barry is knocked unconscious by a punch from Ralph Dibny.
Cisco detects an interference on the electromagnetic spectrum wavelength for red light, He intuitively thinks this and an odd series of storms creating red skies and yellow lightning have something to do with Ollie and Barry's "shared psychosis."
Shortly after discussing the weird weather with Caitlin, Cisco reflexively vibes The Monitor giving the book to Dr. John Deegan.
The cells in STAR Labs pipeline do have toilets. The seats fold up into the walls when not in use.
Oliver teaches Barry how to dislocate his thumbs to escape a pair of handcuffs.
Barry teaches Oliver how to use his speed to phase through a wall.
Barry finally convinces Iris that he and Ollie really did switch places by telling her the first thing he said when he moved into her home when he was 11 and calling her by his pet name for her - Lightning Rod.
Lois Lane went to Argo City with Superman.
Kara refers to the events of S408 and how she was fired from the DEO after a confrontation with President Baker.
Clark has something he wants to ask Kara before Barry and Oliver show up.
Kara recognizes Barry and Oliver as who they really are.
The Amazo robot is able to use Killer Frost's powers to fly.
The trap Barry rigs up to that shoots Oliver in the back is a reference to F108, where Oliver created something similar in his efforts to train Barry.
Lois Lane thinks Oliver Queen is a jerk.
Oliver discusses how he channels his anger when he fights. Barry, by contrast, draws on his inner joy to use his powers.This causes Ollie to realize he wasn't able to phase until he laughed at Barry earlier and Barry had to draw on his annoyance with Ollie to dislocate his thumbs.
Each piece of AMAZO is placed in a separate STAR Labs vault.
Clark returns to Earth-38 at the episodes end.
Sherloque's third ex-wife lives on Earth-38. He asks Clark to deliver an alimony check for him.
The Monitor can sense Cisco watching him through a Vibe vision.
Oliver determines that the place Cisco saw in his vision is Gotham City, based on the presence of the Wayne Enterprises building in the background.
The episode ends with an image of Batwoman standing on a building on Gotham.
Earth 1- Gotham City
Earth 1 - Central City
Earth 1 - Star City
Earth 38 - Smallville, Kansas - The Kent Farm
The Bottom Line
Perfect, despite its imperfections. Yes, there are a few wonky bits with the script. Yes, the presence of Amazo makes no sense given the Arrowverse's earlier version of Professor Ivo. And it seems like Team Flash was WAY too quick to turn on Barry and refuse to believe that Barry and Ollie could switch places given how much weird stuff they've dealt with before. All will be forgiven once you see the fight with Amazo, the chemistry between Lois and Clark and all the other hundreds of little things this episode does right.