And you still thought you'd have to wait until 2017 to see the Justice League, didn't you?
This episode is the fourth of a four-part Crossover event between Supergirl (2015), The Flash (2014), Arrow, and Legends of Tomorrow. The episodes in chronological order are "Medusa", "Invasion!", "Invasion!", and "Invasion!".
After learning the Dominators' plan for the world, the Legends must work together with the Flash, Supergirl, and Green Arrow to kill them once and for all. Meanwhile, Stein figures out, with the help of others, how the team can defeat the Dominators, but is distracted by the aberration he realizes he created in 1987.
Tropes:
- The '50s: Part of the group travels to 1951, when the first Alien Invasion occurred.
- Accidental Aesop: Happens In-Universe in this episode. Dr. Stein recounts the story of Androcles' Lion, but he seems to think that the moral of the story is, "big enemies can be hurt by little things."
- Age Cut: A cut from 1951 to the present day is used to show past Mr. Smith is the belligerent government official menacing the Flash and company, still wearing the same horn-rimmed glasses.
- And Starring: The "Special Guest Stars" lineup ends, "With Melissa Benoist and Grant Gustin."
- Annoying Arrows: Oliver shoots two arrows into a Dominator, which at best is inconvenienced by them.
- Answer Cut: Barry tells Oliver that they should hang out more often, not just when the world is in danger. Oliver then asks him what they would do if the world didn't need saving. The answer is drink.
- Ascended Meme: The Arrowverse finally acknowledges the strong resemblance between Felicity and Kara (in her civilian attire) that fans noticed since Supergirl first began airing.Felicity: It's like looking into a mirror.
- The Atoner: Barry is willing to sacrifice himself to the Dominators in part to atone for creating "Flashpoint".
- Big Damn Heroes: "Y'all called for Tech Support?"
- Blatant Lies: The Dominators claim that turning Barry over to them will make them go away, but it's clear they are fully intending to launch the metabomb anyway since their issue is with the existence of metahumans overall, not just Barry.
- Bookends: With the Supergirl episode, which also features a powerful bioweapon that targets a certain group (aliens, in the earlier case).
- Brick Joke: Heat Wave calls Supergirl "Skirt" just as he promised two episodes back.
- Bullet Catch: Barry does this with almost contemptuous ease. Then he turns the bullet around and allows its momentum to carry it into the shooter's shoulder.
- Bullying a Dragon: The CIA trying to capture The Fastest Man Alive, a guy in Powered Armor, and two of the biggest Badass Normals in the world. This couldn't end well.
- Chekhov's Gun:
- Averted. It was widely speculated that the alien-killing bioweapon, Medusa, introduced in the Supergirl episode that began the crossover would be employed against the Dominators (especially with Supergirl revealing in The Flash episode that they exist in her universe, too). Ultimately, while the episode does feature a bioweapon targeting a specific group, it's deployed by the Dominators, who are subdued using a totally unrelated method.
- Played straight with the "breach crosser" Cisco gives Kara, as it was announced before this crossover aired that “Duet” would happen.
- Cold-Blooded Torture: Mr. Smith looks almost gleeful at the idea of testing how closely a Dominator nervous system is similar to a human's by inducing pain.
- Conflict Ball: Ollie develops a sudden and inexplicable dislike for Supergirl just so that she can have her own subplot based on an interpersonal conflict (like the other main characters have in this crossover), and also because the missions would have gone differently if she was allowed to participate. This conflict then gets solved as quickly as it was introduced, when Kara saves Ollie's life in the final battle.
- Continuity Nod: See The World Is Always Doomed.
- Cry for the Devil: When they hear him screaming in pain, Cisco decides that the group should rescue the Dominator from his torture. Unfortunately, rescuing it in 1951 means that the Dominators in the present day know Earth has metahumans.
- Curb-Stomp Battle: Mister Smith and his agents, all normal humans with normal guns, trying to arrest a metahuman who is The Fastest Man Alive, a man in a flying suit of powered armor, and two of the deadliest "normal" humans on the planet when it comes to close-quarters combat? Guess how that works out for him.
- Does This Remind You of Anything?:
- Caitlin and Prof. Stein's discussion about the latter's daughter being a Time Aberration and the implication that she should be erased is essentially like discussing abortion or disposing of an unwanted child.
- The word itself isn't outright said, but the others react to Barry's decision to give himself up to the Dominators like he's about to commit suicide.
- Dramatic Irony: The Dominators are fixated on metahumans with powers being a threat to them, when critical components leading to their defeat are human technology (the pain emitters, the Waverider, Ray's suit, Mick's gun), regular although very smart human minds (father and daughter Steins, Felicity, Cisco, Curtis, the developers of the chip they took from Cyberwoman), human willpower, Badass Normal heroes, and a friendly alien, although Cisco's meta powers are equally important. Furthermore, either they're unaware or conveniently ignore that there's another speedster out there who is just as capable and a lot more willing to cause damage to the timeline than Barry: Eobard Thawne.
- Embarrassing Rescue: Heat Wave laments being rescued by "nerds".
- "Eureka!" Moment: After Lily complained how Stein is avoiding her, he awkwardly apologizes that his life has become complex. They suddenly figured out that the reaction of their nano-technology requires greater complexity to work (via exponential instead of sequential).
- Event Title: Due to the ongoing Alien Invasion.
- Fantastic Racism: The Dominators believe all Metahumans are a potential threat, invoking the Superhero Paradox.
- Finger Poke of Doom: At super-speed, Barry just has to lightly nudge one of the MIB guys to knock him flat.
- Foreshadowing: Cisco gives Kara a "breach crosser", allowing her and her allies to initiate the crossover when necessary.
- Forgiveness:
- Discussed when Barry asks Diggle if he forgives him for Flashpoint erasing Baby Sara. Diggle responds that Barry needs to forgive himself for what happened.
- Cisco forgives Barry for Flashpoint and his brother's resulting death.
- Gilligan Cut: When Barry suggests they should hang out more often, Oliver asks what they could possibly do that wouldn't involve some kind of threat to the world. Smash Cut to the two of them sitting in a bar just having a beer.
- The Greatest Story Never Told: Invoked in universe when the President states that the true story of how the invasion was repelled will be classified, but the people in charge know who the planet owes for its survival.
- Heroic Sacrifice: Barry is more than willing to hand himself over to the Dominators if it means they will leave Earth. Fortunately for him his friends are having none of it.
- Identical Stranger: Felicity notes how much she and Kara look alike when she sees the latter wearing her normal clothes.
- I'd Tell You, but Then I'd Have to Kill You: Mr. Smith says this to the Flash and the other heroes he's with, which would sound badass if he weren't so utterly clueless as to how outmatched he is.
- Improbable Age: Mr. Smith is shown to already be in a position of authority back in 1951, which means he must've been at least in his thirties back then. This means that in 2016 he's 95 years or older, but he's still virile and working, and the actor hardly looks that old.
- Improbable Aiming Skills: During the Curb-Stomp Battle against Smith's Mooks, Oliver fires an arrow off the ground under a van and into the ankle of a gunman taking cover behind it.
- Internal Reveal:
- Stein reveals to Caitlin that Lily did not exist in the original timeline and then reveals to Jax that she exists as a result of Stein meeting his younger self in 1987.
- Cisco learns about Firestorm's matter transmutation abilities.
- It Has Been an Honor: Barry says this word for word as he prepares to hand himself over to the Dominators.
- Jerkass Realization: After Cisco goes back to 1951 and saves the captured Dominator from torture and death, he's informed by the same Dominator in 2016 that its escape resulted in the confirmation of the existence of metahumans on Earth. Cisco recognizes he altered the timeline for what he thought was a good reason and thus he bears some responsibility for why the Dominators came back to Earth in 2016 to wipe out Barry and all metahumans. This makes him realize that he can't continue to blame Barry for doing the same thing when his own actions could have a result—millions of deaths, if not the total extinction of humanity—immeasurably worse.
- Know When to Fold 'Em: The Dominators beat a hasty retreat after their metabomb is turned into a large puddle and their ground forces simultaneously experience crippling pain. Earth's metahumans may be a threat, but now it's clearly one beyond their ability to stop.
- Leaning on the Fourth Wall:
- Oliver and Sara discuss how it used to be that they were the ones considered extraordinary before the arrival of metahumans, time travel, and aliens.
- Oliver mentions there were no witnesses to his second fight with Barry.
- Right after Felicity notices how much she and Kara look alike, Ray mentions that she kinda looks like his cousin. Brandon Routh played the Man of Steel in Superman Returns.
- Meanwhile, in the Future…: There are several cuts back and forth between the 1951 team and the people who stayed behind in 2016.
- The Men in Black: Mister Smith is all over this trope. Also, at the end, Kara tells the President about the DEO on her Earth, and the President likes the idea, which may lead to such an agency being founded on Earth-1 as well.
- Misery Builds Character: Kara gives a relatively hopeful version of this when encouraging Oliver toward the end of the episode.
- My Friends... and Zoidberg: Felicity towards Barry, much to his disdain.Felicity: This looks like a job for Supergirl!
The Flash: Thanks, Felicity. I'm not the least bit insulted.
Felicity: Ah, sorry. I meant Supergirl and Flash. This is totally a job for the both of you. - Mythology Gag: Felicity uses the "This is a job for..." phrase to Supergirl (and Flash) that is popularly used to refer to Superman.
- No Good Deed Goes Unpunished: By saving the Dominator in the past, Cisco shows them that metahumans exist on Earth and are a threat.
- "Not So Different" Remark: At the end of the episode, Cisco forgives Barry because he also unwittingly made things worse by changing the past.
- Offscreen Moment of Awesome:
- After the events of the last episode, Oliver, Ray, Sara, Diggle, and Thea had their costumes/suits replaced with unisex grey clothing after the Dominators abducted them. Here, their costumes/suits have returned. While at least part of this can likely be chalked up to the Waverider's ability to create new clothing, Ray's A.T.O.M. suit definitely can't, so the fact that he once again made a new A.T.O.M. suit from scratch in a very short period of time is extremely impressive.note
- After the Legends that traveled back to 1951 are captured, Cisco and Felicity manage to fight their way to where they are with some guns they found on the ship. All we hear of it is some shooting noises before they burst in through the door.
- After she is basically benched by Oliver for a time, Kara apparently gets very angry. We don't get to see this rare event, we just get to hear Barry describe it.
- Out-of-Character Moment: Many fans were confused as to why Barry, who has lost both of his parents over the course of the show, did not say goodbye to Iris, Joe or Wally before he decided to give himself up to aliens, or even discuss it with them before he did it. As emotional as he gets about losing people he loves, this was deemed OOC by a lot of people. Marc Guggenheim later confirmed that Barry instructed Felicity to tell Iris that he loved her and apologizes for not saying goodbye, but the scene was cut for time.
- Overshadowed by Awesome: Other than Mick, who has a flamethrower powerful enough to hurt the Flash, the Badass Normals are barely a threat to the Dominators. Oliver is even nearly killed by just one of them.
- Pet the Dog: Ungrateful Bastard he might be, the Dominator rescued by Cisco's group still wants to spare them in return, and even genuinely praises Cisco's own power.
- President Minority: The new president is a Twofer Token Minority, being both female and African American.
- Reassigned to Antarctica: Kara tells Mr. Smith that she had a talk with the President and this will literally be his fate if he tries to do anything to her friends.
- Relationship-Salvaging Disaster: Cisco's own time travel and salvation of someone who would attack the Earth made him comprehend why Barry refuses to save his brother Dante.
- The Reveal:
- Barry and Oliver's bar chat reveals that Barry won the sparring match between them at the end of their first crossover. Though Oliver notes there were no witnesses so he can always deny it.
- The Dominators know about Flashpoint and that Barry was responsible, though it's not explained how.
- Smith knows all of the heroes' secret identities.
- Stein's daughter is named Lily.
- Ripple-Effect-Proof Memory: An extremely tragic example of this trope. Prof. Stein has no memory of his daughter because from his perspective, she only just started existing. However, from everyone else's perspective, including Lily herself, Stein has been a loving father to her for nearly 30 years. This is similar to how Barry has supposedly "known" Julian Albert for over a year despite just meeting him from his perspective, although portrayed in a considerably more serious light.
- Save the Villain: Cisco decides to rescue a Dominator that got captured by The Men in Black. Unfortunately, this is what leads to the invasion happening in the present.
- Screw the Rules, I'm Doing What's Right!: Stein initially plans to erase his daughter by fixing what he changed, but decides against it and asks Jax not to tell the others.
- Screw This, I'm Outta Here: When the metabomb is destroyed, all the Dominators decide to flee.
- Secret Identity: At the celebration party after the Dominators' defeat, Kara dresses in her civilian clothes, even though there's no need for her to maintain her secret identity in this scenario.
- Sequel Hook: Variation as Cisco gives Kara a device that allows her to communicate and travel between Earth-38 and Earth-1, making crossovers in the future simpler.
- Serial Escalation: Oliver, Sara and John all point out at one point how it used to be just a world of Badass Normal people in the beginning. Then came the metahumans. And now there are aliens.
- Shout-Out:
- Mister Smith refers to the Dominators as Xenomorphs.
- When Felicity is stuck temporarily speaking gibberish due to temporally-induced aphasia, one of the random things she yells is "DarmokAndJaladAtTanagra!"
- Kara calls her new friends "Earth's Mightiest Heroes". Uh, wrong team...
- Nate quotes The Princess Bride: "I'll take that as, 'Have fun Storming the Castle'." Given a Lampshade Hanging by Cisco in this case.
Cisco: Oh, for real? You're gonna use Princess Bride against me? Against ME?! - Special Edition Title: All three parts of the "Invasion!" crossover arc (excluding Supergirl) have special title cards. This and the first part combine all four series' logos, but this being a Legends of Tomorrow episode, ends on its own title.
- Spotting the Thread: Perhaps thanks to how she saw Barry having the same reactions when he restored the timeline after "Flashpoint," Caitlin sees how Stein is awkward around his daughter, not catching on her obvious references and figures out that somehow, Stein has no idea who Lily is. She confronts him on it so he confesses how she shouldn't actually exist.
- Story-Breaker Power: Supergirl is conveniently not on the trip back to 1951 (where she would have easily saved the team from Smith and his other agents) and not with Oliver's group in 2016 when they're ambushed by Smith and which ended up being a Curb-Stomp Battle even without her there. To its credit, the episode includes a sequence in which Oliver explains why Kara is being "benched" on these two missions (though for very selfish and self-conscious reasons).
- Time-Shifted Actor: Mr. Smith appears as both a young man in 1951 and an old man in 2016, played by two different actors wearing the same glasses.
- Took a Level in Badass: Firestorm is now able to transmutate larger objects, with difficulty.
- Ungrateful Bastard: The Dominator saved by the group in the past, while saying that You Will Be Spared, refuses to do the same for Barry.
- The Unmasqued World: The government and ARGUS may have covered up the existence of aliens before on Earth, but yeah, good luck with that now.
- The Unreveal: Referenced in-universe when Oliver claims he can take Barry, and Barry's claim their previous two fights prove otherwise are wrong because the first time they fought it was a tie (even though it didn't really come off as one on Barry's end), and the second time there were no witnesses. However, the way Oliver says the latter, it is made clear that Barry won that second one.
- Vomit Discretion Shot: Felicity pukes twice in the Waverider, but nothing is shown. As he is leaving, Rory tells Cisco to clean it up, with a tone of "hey, she's your friend."
- Waxing Lyrical: Cisco and Felicity briefly quote the lyrics to "One Two Step" by Ciara.
- Well-Intentioned Extremist:
- The Dominators only want to kill all metahumans on Earth, even if it means killing several million normal humans along with them, as they claim metas on other worlds have gone on to cause massive destruction if left unchecked and fear humanity could do the same, especially since Barry can travel through time of his own free will. It doesn't explain why their cousins attacked Krypton-38, since Kryptonians only get their powers from yellow suns, but that may have been a simple reconnaissance mission like the first attack on Earth.
- Agent Smith might be a huge, unrepentant dick (especially in the past), but in the end, he just wants to ensure the safety of the planet.
- Where It All Began:
- Part of the group travels to 1951 during the first Alien Invasion.
- Sara also mentions to Oliver that the whole adventure (The Arrowverse) started when the two of them got on the Queen's Gambit.
- What Measure Is a Non-Human?: Addressed in Lily. As far as Stein is concerned, she's just a "time aberration" and he intends to erase her as soon as possible. Caitlin presses him to understand that Lily is a real person who loves her father dearly and her existence can't be forgotten like that. Talks with Lily make Stein realize his life is better with her and to let her stay even if he can't remember her.
- The World Is Always Doomed: Lampshaded.Kara: Either of you ever save the world before?
Barry: Mmhm.
Oliver: Last year.
Kara: It doesn't get old, does it? - You and What Army?: Barry asks this when Oliver insists that he won't be allowed to sacrifice himself. All Oliver has to do is indicate the assembled heroes, who are just as set against the idea.
- You Watch Too Much X: Felicity notes that maybe Cisco watches too much TV when he takes the idea that The Men in Black will invoke They Would Cut You Up from Stranger Things.
