Sentenced to perform one good deed for every person he ever tormented, Mister Mxyzptlk shows up on Kara's doorstep ready to bend reality to her will. It sounds too good to be true but after checking the fine print of the bargain, Kara agrees to let Mxy rewrite history so that she revealed her secret identity to Lena Luthor before it ruined their friendship forever. Unfortunately, every attempt at making things right only makes things worse!
It's A Wonderful Life (title and basic theme of rewriting the past only to realize you're better off with the present.)
The alternate timelines are largely based around events that should probably have played out differently in the post-Crisis reality. There is no reason, for instance, for Mercy Graves to attack LuthorCorp or for the Children of Liberty to be established in a world where Lex Luthor has never been a convicted criminal. (It's probably best to assume that Mxy is playing around with the pre-Crisis world given that he seems to regard Kara's past as episodes of a popular TV show.)
There's no explanation for why Winn, in his Legion uniform, is around when Lena is kidnapped by the Children of Liberty in the third alternate timeline.
There's no explanation for why Winn and Mon-El are present in their Legion uniforms in the timeline where Lena and Supergirl never met.
Thomas Lennon is an instantly engaging presence as Mister Mxyzptlk and you almost wish he hadn't turned over a new leaf so we could see him in action against Kara and Clark in the future. Still, if this is the last time we see Mixy in the Arrowverse, it's a solid final appearance.
Props to the design team for the flawlessly designed "Mxyflyx" website we briefly see on Kara's laptop Mister Mxyzptlk starts streaming her life like a TV show.
When Mister Mxyzptlk returns after being sent away, he says "Thank Zook you changed your mind!" Zook was the name of an alien being who acted as a pet/sidekick to J'onn J'onzz. Zook was a creature that resembled a cartoonish dog, who had the powers of temperature manipulation (he could freeze or super-heat objects he touched), limited shape-shifting abilities and he could track anyone whom he had met before, no matter how they had disguised themselves.
Curiously, in 315, M'yrnn J'onzz said that J'onn's imaginary friend as a child was a 5th Dimensional being named Zook, who did mischievous things and blamed J'onn for them. This may suggest that Zook is a real person in the Arrowverse, as Zook was also mentioned in 213 (along with a Zook Uprising on Mars) and J'onn made reference to fighting a 5th Dimensional being once.
The BetaMyx tapes detailing Kara and Lena's friendship are labeled with titles that parody the format of the titles of Friends episodes. (i.e. The One Where It All Began, The One With The Lesbian Wedding, The One Where Ross Finds Out.). Some of the episodes we see are titled The One Where Lena Moves To National City, The One Where Supergirl and Lena Fight The Nanobot Lady and The One Where Lillian Admits She Loves Lena.
This episode confirms a fan theory that the magical hat utilized by The Hat from The Elite belonged to Mister Mxyzptlk, who normally has a hat in the comics. The Hat claimed to have been told where to find the Fortress of Solitude by someone he called "Mixy" in 414 and Mister Mxyzptlk confirms that The Hat was an old drinking buddy and he lost the hat to him in a poker game.
In the second alternate timeline, Lena creates an electric device that seems to shock Sam's Reign personality into dormancy.
Mister Mxyzptlk: I am offering you a do-over. Hmm? I could send you back in time. Wouldn't you like to be able to tell Lena that you're Supergirl on your own terms? Wouldn't you like to see what the world would look like if you controlled the narrative?
(Suddenly Mister Mxyzptlk is standing behind Kara and Alex. They both jump as he speaks again.)
Mister Mxyzptlk: Haven't you hurt enough? Hmm?
(Kara just glares at Mister Mxyzptlk)
Mister Mxyzptlk: I get it. You don't trust me. Okay. But how's this? Ready?
(Mister Mxyzptlk pulls out a recorder, which he hands to Kara. She inspects the recorder as he keeps talkling.)
Mister Mxyzptlk: Now, by Fifth Dimensional law, I am required to give you this recording of me saying my name backwards, in case you ever need to banish me to my Fifth Dimension, which I know that you-
(Kara pushes the play button on the recorder.)
Mister Mxyzptlk: (on recorder) Kltpzyxm.
(Mister Mxyzptlk makes a face and poofs into a cloud of glowing blue smoke.)
Lena: When you were Reign, and I made Kryptonite to stop you You know, in response, Supergirl was so horrible. And then, Kara was the same. She was so kind and supportive. But it made me think, which was the real Kara? And if the real Kara thought I was a villain then maybe that's all I really am.
Sam: No, Lena, no. How could you ever think that? Lena, you made Kryptonite to split me from Reign and to save my life. You were never the villain. You were always the hero.
Supergirl: You once told me Kara Danvers was your hero.
Lena: I never told you that. I told
Supergirl: It's me, Lena. I've always been Kara.
Lena: Kara, how could you?
Supergirl: I'm sorry I didn't tell you sooner.
Lena: Three weeks ago, I found out that Sam, one of my closest friends, was a homicidal Kryptonian. I went through that terror alone. I risked my life day after day for weeks because I believed that I was the only one who could be trusted to protect her, to save her. I could have used your help. I would have used your help if you'd bothered to tell me the truth before now. If you'd trusted me then, I wouldn't have had to go through that danger alone!
Supergirl: I'm so sorry, but I thought I was protecting you. But now, we can... we can move past it and work as partners.
Lena: (angrily) You expect me to be your partner after this?! When all you've done is prove to me that you can't be trusted at all?
(Mister Mxyzptlk is fast fowarding through a lot of the fight with Reign and Supergirl.)
Kara: Wait. You're skipping a lot!
Mister Mxyzptlk: This is all exposition, so much exposition.
Mon-El: You know, Lena and I have a lot in common. We've both been betrayed by our own families. And when the people who are supposed to love you the most let you down, it just makes you feel so so vulnerable, you know? But my mother and the Luthors, they betrayed Lena for their own selfish reasons. They They wanted to take advantage of her. You lied to to protect her. Because she's your friend. Now, I know Lena's hurting right now, but once she understands that she'll forgive you.
Supergirl: I hope you're right. But I don't think I'll ever be able to forgive myself.
Mon-El: You know it's okay to mess up, right? No matter how many mistakes I've made, you've always forgiven me. You should, uh, know that you deserve the same compassion that you show others.
Lena: I didn't come here to make friends.
Kara: I wanna show you something.
Lena:Listen, I'm really busy, so, if we could just-
(Kara flies out the window at super-speed. She is standing there a moment later. Lena is stunned.)
Lena: It's you! Kara Danvers is Supergirl.
Lena: Can't believe I was fooled by a pair of glasses.
Kara: Don't worry, a lot people are.
Lena: Oh, God, (chuckling) I have to recall all those alien detection devices 'cause they clearly don't work.
Kara: You're not angry?
Lena: No, it's incredible. I mean, you're incredible! But... why are you trusting me with such a big secret? You barely know me.
Kara: Because I know that what you want more than anything is to do good. And I know it's hard for you to trust people, but I need you to know now, without a doubt, I trust you. My cousin, your brother, they got it wrong. Imagine what we could do together. A Luthor and a Super, working together as a team.
Lena: If we were partners, we could change the world.
(Kara smiles and offers her hand. Lena shakes it. Suddenly, we see a number of spinning newspapers talking about the amazing things Supergirl and Lena Luthor have done together.)
Mister Mxyzptlk: (in an old time radio announcer voice) Only months after publicly declaring their partnership, the formidable duo of Supergirl and Lena Luthor has already cleaned up National City's criminal element. This pair is literally unstoppable! Not to mention, fashionable after Lena convinced Supergirl to cut the hair of steel, and gave her a new suit to boot. But their next adversary is Lillian Luthor herself, and this time, their battleground is a courtroom. Emotions. Drama. Will they persevere?!
(Cut to Kara's living room where she's hitting the side of the TV trying to get the picture to unstuck. Mister Mxyzptlk is standing there dressed as a 1930s Newsie, talking into an old-fashioned microphone.)
Kara: Mxy, can you please take this seriously?
Mister Mxyzptlk: (still talking in an old time radio announcer voice) Take it seriously, because every party needs a pooper, and that's why we invited Kara!
(Supergirl looks around the CatCo offices that are now Lena's base of operations.)
Supergirl: Lena? It's me. It's Supergirl. It's Kara.
Lena: (coldly) Who's Kara?
Mister Mxyzptlk looks quite different from how he appeared in 213. He explains that this is because he adopted a form he thought Kara would find more pleasing when he was trying to romance her.
Mister Mxyzptlk says that he was put on trial for abusing his powers to torment people, including Kara. His sentence was to lose his powers except in so far as he used them to do one good deed for every person he wronged. Kara is the last person on his list.
Mister Mxyzptlk suggests that Kara can use her free wish to rewrite time so that she gets to choose when Lena found out about her secret identity.
In addition to being magically unable to use his powers except to help people he wronged, Fifth Dimensional Law also requires that Mister Mxyzptlk give a recording of himself saying his name backwards to the person he is trying to help so that they can get rid of him at any time.
Mister Mxyzptlk is also court-ordered to restore things to normal should Kara not be happy with the results of her wish and is happy to walk her through her life and find the perfect point to change everything.
Kara decides to take Mister Mxyzptlk's help, purely because Lex and Lena are planning something together, they have no idea what and restoring Kara's presence in her life may be the only way to stop her.
Alex and J'onn are sent away to play paintball while Kara and Mister Mxyzptlk work together.
The first alternate reality is viewed on a movie screen and projector which Mister Mxyzptlk conjures into Kara's living room. He also makes popcorn.
Kara and Mister Mxyzptlk rewatch the scene where Kara pretended to be helpless while secretly saving her and Lena from a jet crash in 420.
The first alternate reality Mister Mxyzptlk creates is based around 402 and Kara revealing her secret identity to Lena shortly after President Marsdin resigned after being outed as an alien, but just before Mercy Graves attacked LuthorCorp. When Kara returns after repelling the attack, Lena is gone. We discover that Lena flew to Metropolis to pour out her heart to Samantha Arias. This meant that Lena was not close-by when Mercy seeded Earth's atmosphere with Kryptonite and was not there to develop the super-suit that kept Kara alive until the atmosphere could be cleaned.
This reality makes Kara think the problem is her hypocrisy in treating Lena differently in both her identities.
The second alternate reality is viewed through Kara's laptop on a movie-streaming site called Mxyflyx. (This is clearly a parody of Netflix.)
Kara and rewatch the scene from 317 where Kara asks James Olsen to break into Lena's lab and search for Kryptonite - an action Kara now agrees was wrong.
The second alternate reality Mister Mxyzptlk makes is based around 317 and 318 and has Kara revealing herself to Lena just after she reveals that she discovered that Samantha Arias is Reign three weeks early and had begun synthesizing Kryponite as part of a treatment. Having spent most of the past month agonizing over one of her best friends being a Kryptonian doomsday weapon, Lena turns on Kara when she reveals that she is Supergirl. This means that Lena doesn't work with the DEO to fight the World-Killers at first, which means they fail to stop the eclipse triggered by the World-Killers working together. This also means that Mon-El remains in the past, due to Pestilence not dying. In the end, Lena joins Mon-El and Kara in the fight against Reign at the Arias Farm, but she, Samantha and Mon-El die in the process.
This reality makes Kara think the problem wasn't the hypocrisy - it was her lying to Lena in the first place.
The third alternate reality is watched on Kara's TV on video tapes (aka Betamyx) after the inter-dimensional WiFi begins buffering.
The third alternate reality starts off with a flashback sequence from 506 and Kara revealing her secret identity to Lena shortly after they first met, sometime during Season 2. The two agree to become partners in making National City a better place. This leads to an alternate take on Lillian Luthor's trial from 212, with Lena refusing to reveal Kara's secret identity under oath while testifying against her mother. This causes Lena to experience a level of public popularity that she never did in the original timeline, and people see her as more than a supervillain in training. It also has the side effect of turning the Cult of Rao from 304 into a more benign religion and less of a doomsday cult. This new Cult of Rao wins over all of the Lockwood family except Ben Lockwood (aka Agent Liberty), who forms the Children of Liberty after his father, son and wife all jump off a roof expecting Supergirl to save them. In a mirror of his confrontation with Lena in 403, Agent Liberty kidnaps Lena and Coville and threatens to kill them both if Supergirl doesn't reveal her secret identity to the world. Kara does so, and Agent Liberty is true to his word and releases Lena and Coville. Unfortunately, the Children of Liberty kill everyone who is close to Kara immediately after that.
This reality makes Kara think Lena would be better off if they'd never become friends at all.
The fourth and final alternate reality is a world where Kara and Lena never met in 201. In this reality, Supergirl isn't there to stop Lena's helicopter from being shot down. She survives the crash, but is spirited away to Cadmus by Lillian Luthor and becomes a rest subject for her Metallo program. Two years later Lena escapes, kills Lillian and Lex, and destroys half of National City in the process. She rules what is left of the city with an iron fist and turns the Lexo-Suits into robots under her control running the Hope AI. All of her technology is powered by tapping into the energy of the Fifth Dimension, which leaves Mister Mxyzptlk powerless until they recover his hat.
J'onn wields the Staff of Kolar, last seen in 415, during his fight with Reign.
Kara decides that she can't change the past and that she'll always have to face the consequences of her actions, but she says that Mister Mxyzptlk helped her to get over her guilt regarding Lena, so she frees him from his obligation.
Mister Mxyzptlk apologizes for being a creep before and thanking Kara for letting him feel like a hero in the bad reality.
Kara tells Lena that she's done feeling guilty over the past and that whatever happens between them in the future is on her.
Mister Mxyzptlk was put on trial for his crimes against Kara and other people he mistreated sometime after the events of 213. He has spent the last three years using his powers to make amends for his crimes, having saved Kara for last.
The Bottom Line
A fun anniversary special and look back at the show's history that may not hold up logically but it's a serviceable tribute to what came before.