Now knowing Savitar's identity, Cisco tries to alter Barry's brain to protect him...only to suffer unintended consequences.
- Amnesia Episode: After Barry learns that one of his time remnants is Savitar, Cisco builds a machine to prevent Barry from forming new memories, so Savitar will not know their next move. This however ends up wiping out Barry’s entire memory, leading to a literal Forgot About His Powers.
- Anguished Declaration of Love: While unsuccessfully trying to convince Caitlin/Killer Frost to stay at S.T.A.R. Labs after Savitar and Barry regain their memories, Julian confesses his love for Caitlin.
- Animated Armor: Barry tries to attack Savitar while he's out of his armor, only for the suit to attack him.
- Arc Words: The episode title itself (see Terminology Title below for details).
- Ascend to a Higher Plane of Existence: According to Barry, Jay was wrong; it is very easy for meta-humans, especially Speedsters, to claim God status. Makes sense since technically all it would take is to have worshipers, because they already have amazing powers. Plus there are plenty of Mythological Pantheons where the gods who made it up only ruled over one or two things; Sky, Fire, Sea, etc, were very petty and emotional and could be harmed or killed. Thus it wouldn't be surprising if in the Arrowverse those Pantheons were actually just metahumans with very large egos, similar to Clyde Mardon.
- Atrocious Alias: Julian cringes at the Heat Monger moniker, only to earn him a glare from the man himself. When Cisco says that he likes the name, the perp actually calms down.
- Batman Grabs a Gun: Barry, who usually always tries to find a non-lethal way to deal with his enemies, tries to outright snap Savitar's neck and would have gone through with it had his armor not saved him.
- Beam-O-War: Savitar and Flash both throw lightning at each other in the beginning, which causes an explosion.
- Big Damn Kiss: Between H.R. and Tracy. Also between Barry and Iris.
- Birds of a Feather: H.R. and Traci are so alike that it even gets lampshaded.
- Bittersweet Ending: Barry gets his memories restored which also restores Savitar's as well. But Tracy finishes the Speed Cannon, and there are hints that Caitlin Snow is Fighting from the Inside.
- Blatant Lies: Caitlin claims she never loved anybody from the Team at all. She is later seen clearly distraught over her conflicting loyalties.
- Breather Episode: After how depressing the past couple of episodes have been, this one brings back some levity in spite of The Reveal on who Savitar is. Borders on Filler since the story doesn't really progress at all.
- Brought Down to Normal: Barry's amnesia means that Savitar also has amnesia, which means that he never knew to enact his plan, which means that he never bestowed the Flashpoint-era powers onto anyone. This means that Wally loses his speed until Barry's memory is restored.
- The Bus Came Back: King Shark returns in the final scene after last appearing in Season 2.
- Cisco mentions Eobard Thawne/"Dr. Wells", Ronnie Raymond and Hartley Rathaway.
- The Flash's initial moniker of The Streak is brought up again.
- Chekhov's Gunman: Remember how Future Barry mentioned that Savitar killed most of the time remnants his past self created to stop Savitar? The sole surviving remnant? Savitar himself.
- Chekhov's Lecture:
- Before letting Barry into the memory altering device, Cisco remarks that Caitlin is the expert on neuroscience. When they botch the operation and they turned Barry (and by extension, Savitar) into an amnesiac, Killer Frost offers a Deal with the Devil to restore Barry/Savitar's memories.
- Before giving the "transmitter specs" to an amnesiac Barry, Julian specifically told him that it's very sensitive to any forms of liquid. Once Barry starts sweating, it immediately jams.
- Cliffhanger: The way to power the Speed Force Bazooka is a power cell from a Dominator ship, which is in A.R.G.U.S. custody guarded by King Shark.
- Cloning Blues: Savitar reveals that he is a time remnant created by Future Barry to fight Savitar. However he survived the fight and was subsequently rejected by Barry and the rest of Team Flash. This breaks this time remnant Barry and ends with him Jumping Off the Slippery Slope and becoming Savitar himself.
- Continuity Nod:
- Savitar points to Eddie Thawne's Heroic Suicide (and Eobard Thawne still existing in spite of it) to talk Barry out of killing himself.
- Cisco refers to the message from "Invasion!" that (the good) Future Barry sent the Legends, concluding that he was trying to warn them about Savitar.
- Cringe Comedy: Barry's testimony at the hearing—due to his amnesiac state and Julian having to feed him his lines.
- Curbstomp Battle: Once they both get their powers back, the Flashes dispose of Heat Monger in a matter of seconds.
- Deal with the Devil: Killer Frost offers to help Team Flash restore Barry's memories so Savitar will also regain his.
- Death Glare: Heat Monger gives one to Julian when he chuckles over his nickname.
- Deity of Human Origin: Savitar strives to be this so that he doesn't have to feel emotional pain.
- Enemy Mine: Killer Frost helps Team Flash restore Barry's memories, if only to restore Savitar's own memories.
- Enemy Rising Behind: During the clash between the Flash and an unarmored Savitar, Barry puts his enemy in a headlock, not noticing Savitar's armor coming to life to assist its wearer.
- Epic Fail: Despite Julian and Cisco's best efforts, an amnesiac Barry testifying in Heat Monger's trial failed as horribly as everyone predicted.
- Fallen Hero: Savitar was once a genuinely heroic time remnant of Barry.
- Fighting from the Inside: The ending suggests that contrary to what Killer Frost claims, Caitlin Snow still exists and is struggling to regain control.
- Flat Character: Heat Monger doesn't really get any characterization at all.
- Savitar tells Barry that Thawne is still alive despite Eddie's heroic suicide.
- Before getting Barry into the memory altering device, Cisco tells everyone that things would be much easier if Caitlin is still around since part of her specialty is neuroscience.
- Freudian Excuse: Savitar, as a time remmnant, felt rejected by Barry and his friends in the future.
- "Friends" Rent Control: Lampshaded; when Barry sees his apartment he wonders how in the world he could afford it. Note that it's been implied that as owner of S.T.A.R. Labs, Barry actually has a lot of money.
- Gone Horribly Right: The team very quickly discovers that giving Barry amnesia was not a good idea.
- Handwave: Savitar claims that the more you time travel, the less the rules apply to you. Not only does that explain quite a bit of the previous inconsistencies with time travel, but also Savitar's and Barry's actions here. Savitar can't kill Barry because it would almost certainly erase him from existence. But there's still a reasonable chance that Savitar would survive, which is why it's too risky for Barry to just kill himself.
- Heroic Suicide: Discussed. Barry points out that he could kill himself and Savitar would cease to exist. Only for Savitar to counter that Eddie tried the same thing to stop the Reverse-Flash and Eobard still came back.
- He's Back!: Once his memory is restored, Barry speeds into action to stop Heat Monger. When he realizes he's not going to be able to put the fire out on his own, Wally rushes in, having his powers restored as well.
- Honor Before Reason: Barry, Cisco, and Julian just let Killer Frost waltz out of S.T.A.R. Labs and go back to Savitar instead of putting her in the Pipeline. It's clear they want her to come back to Team Flash of her own desire.
- Identity Amnesia:
- Barry, thanks to Cisco.
- Savitar does too, predictably.
- Ignored Epiphany: Caitlin clearly has a moment of conscience, when she reminiscences with Cisco. She still returns to Savitar's side in the end.
- Internal Reveal: Savitar tells Barry how he was despised by his Team Flash and that he killed another time remnants.
- Leaning on the Fourth Wall:
- Everyone comments on just how happy Barry is in his amnesiac state. He hasn't been this happy since Season One; a common criticism is just how depressing the show has been in subsequent seasons.
- Savitar's comment that the more you time travel, the less it makes sense also seems like a nod to the fans who are irritated by the inconsistencies of Flash and Legends of Tomorrow's time-travel rules.
- Love Hurts: The main reason for Savitar's Face–Heel Turn, as all the loss in his life made him come to the conclusion that it was better to free himself of any affection.
- Mirror Match: Barry and Savitar have a fight in which they even throw a ray to each other. Savitar says he fought another Barry's time remnants and killed them.
- Motive Rant: The episode starts out with one from Savitar, which essentially comes down to him having the Cloning Blues due to being a time remnant.
- Mythology Gag:
- Savitar's true nature as a clone of some sort as an enemy of the Flash harkens back to Pollux of The Flash (1990), and later Bart Allen's nemesis Inertia/Kid Zoom in mainstream comics.
- In his amnesiac state, Barry insists that he be called Bart. In the comics, Bartnote was his grandson who was Impulse, later Kid Flash II and briefly Flash IV. It's also a Mythology Gag to Smallville, where Bart Allen introduces himself with fake IDs of the other Flashes (Jay, Wally and obviously Barry).
- An amnesiac Barry suggests if they could name him The Streak instead of the Flash, which was an alias for a Jay Garrick Expy in the DC Animated Universe.
- Nice Job Breaking It, Hero:
- Savitar reveals that Barry creating Flashpoint created a ripple that was responsible for the Stable Time Loop of his creation.
- Cisco thought he could find a way to "mute" Barry's memories so Savitar couldn't use them, only to erase all of Barry's memories. It also has the effect of wiping out Savitar's memories as well...and Wally's powers since he got them from Savitar. Oddly Killer Frost doesn't revert back to Caitlin (suggesting that Savitar wasn't 100% directly involved with this change).
- Because of Barry's amnesia, he botches his testimony at Heat Monger's hearing, meaning he will walk.
- Not So Above It All:
- For once, Julian is eager to participate in one of Cisco's experiments. Sadly, that experiment is tampering with Barry's memories. There's also when an amnesiac Barry is testifying in trial and Julian, who is feeding Barry his lines, has Barry compliment Julian, and with a happy face emoticon at that.
- Cecile may have been angry at the timing of Barry's Laser-Guided Amnesia, but she decided to play along.
- Power Incontinence: Amnesiac Barry undergoes one.
- Regained Memories Sequence: When Heat Monger's attack calls for Barry's speedster knowledge, Iris snaps him back by recounting a childhood memory of her comforting Barry the night his mother died, resulting in all of Barry's memories flooding back to him at once.
- Remember the New Guy?: Apparently, Heat Monger got caught by Barry off-screen in-between episodes.
- Replacement Flat Character: He is just a clone of Mick Rory, who is something of a reformed criminal.
- The Reveal: Savitar isn't actually future Barry, he's specifically the one time remnant Barry created to stop Savitar that wasn't killed.
- Ripple Effect Indicator:
- Since Savitar is a future Barry, he loses his memory when Barry does, and regains it when Barry does.
- Because Wally got his powers from Savitar's time loop, the latter losing his memory (and thus not being able to enact the loop) cause him to lose his speed. He gets it back once Barry (and therefore Savitar) gets his memory back.
- Running Gag: Barry really likes the name Bart.
- Sadly Mythtaken: Savitar claims he sought godhood because God doesn't feel pain; though it is true that he doesn't feel physical pain,note the Old Testament does include multiple passages where יהוה, note (That's the name of the Abrahamic God) states he's feeling emotional pain, which is what Savitar was referring to.
- Sci-Fi Writers Have No Sense of Scale: Tracy notes that her Speedforce Bazooka requires 3.86 Terajoules (TJ) of energy, which is an important plot-point as it serves as the main driving point of the next episode. Cisco states that 3.86 TJ is more energy than what the Sun contains. For comparison's sake, the fuel inside an Airbus A330-300 releases about 3.4 TJ of energy, which is just under the required amount. A 20 kilo CANDU nuclear fuel bundle can release 4 TJ of energy, just over what they require. Little Boy, the nuke that exploded over Hiroshima in 1945, released roughly 16 times more energy (~63 Terajoules) than what they required. The Sun, on the other hand, releases enough energy that roughly 1700 Petajoules reaches Earth every second. That is roughly fourty-five thousand times the energy required for the Bazooka.
- Self-Deprecation: Cisco states he hates spinoffs, guess what this show is itself a spinoff, of Arrow specifically.
- Turns out Barry loves Dragon Ball Z.
- Turns out Star Trek: Voyager is the only part of the franchise H.R. knows. Cisco mentions he hates Spinoffs.
- "Shut Up" Kiss: Tracy gives one to H.R. when he won't stop talking.
- Stable Time Loop: Future Barry created time remnants to fight Savitar, who killed all but one of them. That one subsequently underwent a Start of Darkness, eventually going back in time and becoming Savitar in the first place. Cisco has to spell this out and explain the concept of the trope to the others.
- Suspiciously Similar Substitute: Heat Monger is described as a more or less one-dimensional version of Mick Rory.
- Take That!: When Cisco makes his Star Trek: The Original Series Shout-Out, he asks H.R. if there are any Trek shows in Earth-19. H.R. replies Voyager, and Cisco mentions his dislike of spinoffs.
- Terminology Title: "Cause and effect" is a relationship between events or things, where one is the result of the other or others. This is a combination of action and reaction.
- Timey-Wimey Ball: Savitar states this starts to happen the more a speedster time-travels.Savitar: See, that's the thing about time travel, Barry: the more you do it, the less the rules apply to you.
- Title Drop: It's the Arc Words of the episode, uttered in separate occasions by Savitar, Cisco, and finally, Killer Frost.
- The Unreveal: How Savitar got his armor and became connected to the Philosopher's Stone is still unexplained.
- Villain Ball: Heat Monger is apparently so addicted to fire that he goes on a rampage right after being freed of all charges. And in the same city!
- What the Hell, Hero?: Cecile is not amused that Team Flash had to erase Barry's memories. Especially bad timing since he's needed for a trial.
- What Measure Is a Non-Human?: A rather dark example of this trope, as a Time Remnant who survived facing off against Savitar was rejected by 2024 Barry, Cisco and the rest, viewing him as "a disposable hero", the Time Remnant Flash felt so hurt he decided to become Savitar. However, it should be noted that he's not exactly the most reliable of narrators.
- What You Are in the Dark: Even in his amnesic state, Barry is lovable geek with a smile on his face, but still with his desire to help people — what he was before the stress of being a hero got to him.