Barry tries to learn more about the coming Crisis, while Cecile leads an attempt to prove that a metahuman suspect is innocent of the crime she's been accused of.
Tropes
- Advancing Wall of Doom: The Crisis as seen in Barry's vision causes a white wall of death that disintegrates everything in its path.
- Arbitrary Skepticism: Allegra is somehow convinced no one could possibly believe her cousin is back from the dead after everything that's happened in Central City. Justified as she knows how it will look to the police if she tries making the claim.
- Asshole Victim: Mitch Romero. He not only extorts Ramsey for ten times what he originally was supposed to pay for his next batch of dark matter, but when Ramsey tried to take the dark matter with a promise to pay him later, Romero attacked him and was about to shoot him when Ramsey accidentally killed him with his powers. It really makes it hard to feel sorry for Romero when his corpse becomes a zombie.
- Bait-and-Switch: Barry prepares for a scolding from Jay for time travelling again, but this time he actually compliments him.
- Body Horror: Ralph gets hit with a full burst of ultraviolet light by Allegra (i.e completely unfiltered by the atmosphere, like the kind that already causes sunburn) that would kill a regular human and still leaves him looking like he fell into hot coals.
- Brick Joke: As Allegra gets accepted at her new job at Iris's Citizen, Kamilla warns her about touching her donuts, an issue Kamilla had with Ralph earlier.
- The Bus Came Back:
- Gideon comes back, with Barry finally deciding to install a copy of her into his suit.
- Barry consults Jay Garrick to help in his research into the upcoming Crisis.
- Call-Back: Iris references how the future newspaper originally showed that Barry was going to disappear fighting Thawne, not a multiverse-threatening crisis.
- Clashing Cousins: Allegra and Esperanza, even way back, when Allegra wanted out of her gang.
- Clear My Name: Allegra gets blamed for a murder committed by her cousin Esperanza, due to having the same powers.
- Cliffhanger: Ramsey is seen experimenting on Mitch Romero's corpse...which suddenly comes to life!
- Continuity Nod:
- In the recovery bed, Barry tells Joan that she should have used Lady Gaga to wake him up, as a reference to the first episode.
- Nanites, courtesy of Ray Palmer are used to help Killer Frost blend in, normalizing her eyes and voice.
- Crusading Lawyer: Discussed. Cecile is thinking to resign as a District Attorney to become a defense attorney of meta-humans. Joe approves her decision.
- Deliberate Injury Gambit: To defeat Ultraviolet, Barry decides to take her waves head-on to be able to reach her.
- Despair Event Horizon: Barry witnesses around a billion different ways the Crisis can go, and none of them feature both himself and his loved ones surviving. He’s forced to admit the Monitor was right that he has to die.
- Failed a Spot Check: Played for laughs. Ralph Dibny fails to notice that the box of donuts was for Kamilla despite her name being written in the box and eats them.
- Foreshadowing:
- According to Jay Garrick's calculations, a wave of anti-matter is going to engulf Earth-2note , which is what happens in the Season 8 premiere of Arrow.
- Barry's vision shows Cisco suited up as Vibe again, hinting that he'll somehow regain his powers.
- Glass Cannon: Esperanza is powerful, but gets knocked out in a single punch by Barry.
- Justified by the fact that Barry was running hard to push through her assault and force equals mass times acceleration.
- Godzilla Threshold: Due to the danger of the Crisis, even Jay thinks that using time travel to learn about it is necessary.
- Heroic Resolve: After being overwhelmed by Ultraviolet, Gideon advises Barry to retreat. However, after seeing the CCPD's symbol, and recalling Joe's Rousing Speech, he gains the fortitude to stand up and take Ultraviolet down.
- In Spite of a Nail: Jay Garrick, a doppelganger of Henry Allen, found his spouse in Joan Williams, a doppelganger of Nora Allen.
- Internal Reveal:
- Jay and Joan learn that the latter is a doppelganger of Barry's late mother.
- Joe gets up to speed on what's been troubling Barry since the last episode.
- Intrepid Reporter: Joan outright calls Iris this.
- Mushroom Samba: Parodied. When Barry sees the art Killer Frost purchased, he momentarily wonders what was in the painkillers he took.
- Mythology Gag:
- The episode title is the same as the issue of Crisis on Infinite Earths in which Barry died. Joan even reads a poem of the same title that was recited during that iconic death.
- Barry's vision of his death is lifted directly from the comic.
- Nebulous Evil Organization: Whatever shadowy group took Esperanza and trained her to be an assassin.
- Noble Demon: Esperanza tells Barry to get up, as she wants him to die on his feet.
- No Social Skills: Killer Frost has some serious issues in interacting with people properly.
- Nothing Is Scarier: We don't see what occurs in the millions of possible scenarios Barry sees; all we know is that the only one where the multiverse survives is if he sacrifices himself.
- "Not So Different" Remark: Cecile tells Allegra that she too is a metahuman who has a hard time controlling her powers to get her to trust her.
- Old Superhero: Jay is now retired, due to his speed declining.
- 1-Dimensional Thinking: Rather than move sideways slightly to get out of the beam and then close the distance before Ultraviolet, reacting at purely human speeds, can adjust her aim, Barry opts to push directly towards her, blocking the attack with his face.
- One-Man Army: Upon invading CCPD, Ultraviolet completely overwhelms every officer on duty.
- O.O.C. Is Serious Business: Jay has always been Barry's biggest critic when it comes to using time travel, but in light of the impending Crisis, he feels that Barry's justified in using it to get information.
- Out of Focus: Ramsey only appears in two short scenes irrelevant to the episode's plot.
- Power Incontinence: Allegra constantly sees microwaves, gamma waves and radio waves and can't shut it off.
- Prophetic Name: A guy named Mitch Romero ends up coming back as a zombie.
- Resigned to the Call: After seeing multiple scenarios with the only one where everyone survives is if he performs a Heroic Sacrifice, Barry is willing to accept his fate. Iris, however, is still determined to change it.
- Resignations Not Accepted: Esperanza beats up Allegra for trying to leave her gang. Later, she tried to frame her and kill her.
- Screw Destiny: Iris wants Barry to be willing to seek how to change the Crisis.
- Sequel Hook: Whatever organization trained Esperanza to become Ultraviolet is still out there. Barry and the others make it a priority to find them and stop them.
- Shout-Out:
- Barry witnessing countless futures where everybody dies except for one where he sacrifices himself is a clear reference to Dr. Strange doing a similar thing in Avengers: Infinity War.
- Cisco calls Killer Frost a White Walker.
- That Man Is Dead: Ultraviolet claims Esperanza Garcia died five years ago, referring to when she fell into a coma following the Particle Accelerator explosion.
- Title Drop: The poem Joan reads to a recuperating Barry, "A Flash of the Lightning".
- Traumatic Superpower Awakening: Ramsey's powers awaken again when he is threatened by Mitch Romero.
- The Unreveal: We don't know why Ultraviolet was assigned to kill the man who Allegra was accused of murdering.
- Wham Shot: Rosso, trying to conduct an experiment on his first Accidental Murder victim, turns around only to be attacked by the corpse.
- What the Hell, Hero?:
- Defied. Barry thinks that Jay will lecture him about the evils of time travel, but he thinks that Barry did the right thing because of the upcoming Crisis.
- Joe and Cecile argue over what is the right approach with Allegra, calling out each other's methods.
- Worf Had the Flu: Due to still recovering from the time travel experiment, Barry has a tougher time against Ultraviolet than he would've at full strength.
- Writers Cannot Do Math: Barry once again time travels by going slightly faster than Mach 2. Later, his top speed is being pegged at 1/80 of the speed of light, despite having gone FAR faster before.
- You Are Better Than You Think You Are: Joe gives Barry a much needed pep talk after he is in shock after witnessing his impending death.
- You Can't Fight Fate: Barry, after witnessing millions of futures, realizing that he has to sacrifice himself to save everyone else, resigns to his fate. Iris, however, is having none of it. She eventually comes around to accepting it may be the only way.
