Barry needs a power cell from a Dominator ship to power the weapon that will be the key to stop Savitar. A.R.G.U.S. has one, but with Lyla refusing to hand it over, Barry decides to take it himself. He knows he needs help, so he decides to go back in time and recruit his old nemesis turned anti-hero, Captain Cold.
- Actually Pretty Funny: Snart comments that the big Shark Meta being named "King Shark" is "adorable".
- Aesop Amnesia: Lampshaded by everyone, as Barry travels back in time again to get Snart.
- All for Nothing: Despite all of Barry and Team Flash's attempts throughout half the season, Savitar still kills Iris.
- An Arm and a Leg: King Shark's hand is severed thanks to his cell door closing while holding on to Snart, who quips afterwards that he knows the feeling.
- Armor-Piercing Question: Killer Frost asks Savitar why he wants to kill Iris, since he has all of Barry's memories he should remember all the happy times they spent, and how much he loved her. Savitar's response is to give a rant on how he suffered.
- Artistic License – Biology: Snart claims that warm-blooded sharks, such as the Great White, are particularly susceptible to cold temperatures. The opposite is actually true: partially warm-blooded sharks have a stronger resistance to cold than cold-blooded sharks. While severe enough temperatures will still affect them, attributing it to their warm-bloodedness is just plain incorrect.
- Ascend to a Higher Plane of Existence: Savitar told Killer Frost that all she has to do in order to accomplish this is permanently destroy Caitlin Snow; She decides to do this via fighting Cisco a.k.a Vibe.
- The Bad Guy Wins: Savitar successfully kills Iris. And the last we see of the fight between Vibe and Killer Frost, the latter has the upper hand.
- Badass Boast: No speed gun can stop a god. And unfortunately, Savitar is right about that...
- BFG: As its name suggests, the Speed Force Bazooka.
- Bookends:
- The episode opens with and ends with AURORA's "Murder Song (5,4,3,2,1)".
- Iris recorded a Video Will on her phone at the beginning. We don't learn what's on it until the end.
- Brought Down to Badass: Thanks to anti-metahuman technology embedded in the A.R.G.U.S. building's infrastructure, Barry can't use his Super-Speed. He still manages to be an impressive spy without it, first established when he knocks out two highly trained armed guards.
- The Bus Came Back:
- Captain Cold is back; specifically one's who joined the Legends at this point and has completely reformed.
- King Shark as well, though he's still in A.R.G.U.S. custody.
- Lyla also shows up, having last appeared since the Invasion trilogy.
- Harry Wells, when the West Family goes to Earth-2 to keep Iris safe.
- Call-Forward:
- Snart's final words to Barry are "No strings on me." — referencing his last words from the Legends Season 1 Finale (just without the "There are..."). Technically, due to time travelling shenanigans, both a Call-Back and a Call-Forward; from the viewers' point of view, it repeats a line Snart's already said. From Snart's point of view, he hasn't said it yet.
- Iris removes her ring and gives it to Joe for safe-keeping — explaining why she isn't wearing it when Savitar kills her.
- Ceiling Smash: Savitar inflicts this on Wally.
- Celebrity Paradox: Barry and Snart make an obvious Shout-Out to Taken. The inaugural film has Katie Cassidy (Laurel Lance). H.R. has also confirmed earlier in the season that Liam Neeson exists (therefore, also the Taken films) on Earth-19, but whether or not that universe also has a version of Dinah Laurel Lance (as Earth-2 Laurel is currently on Earth-1, she's also affected by the paradox) remains to be seen.
- Chekhov's Gun: Barry uses H.R.'s chameleon tech in order to appear as Lyla.
- Cliffhanger: The episode ends with Savitar killing Iris, Wally's legs broken, and Cisco fighting Killer Frost in the forest.
- Continuity Cameo: Barry and Cold pass Grodd's and Cupid's cells on their way to the vault.
- Continuity Nod:
- Lyla brings up Flashpoint and its consequences — mainly the Dominator invasion as a reason not to trust Barry with the power cell.
- A.R.G.U.S. has power dampeners all over the institute. This is not just because of the rising number of superpowered criminals, but the last Meta we know that was sent to A.R.G.U.S. happens to have one of the most dangerous powers around.
- Cold doesn't see why Barry wants to team up with him again, given he double-crossed Barry last time.
- Savitar is seen tinkering with his suit as it was damaged in his fight with The Flash last episode.
- Barry mentions the Suicide Squad as he passes their former containment cells. When he passes by Grodd's cell, he also brings up the events of their previous encounters.
- Snart comes up with a non-lethal solution to deal with King Shark, a sign of his Character Development during his time with the Legends.
- To escape becoming King Shark's next snack, Snart tries to "bribe" Cisco into opening the cell door faster by putting in a good word with his sister Lisa Snart.
- When the closing cell door severs King Shark's hand, Snart quips that he knows what that's like.
- The Corrupter: Surprisingly subverted with Snart. At first he seems to be bringing out Barry's ruthless side again, even encouraging him to leave him to die...but in the end, he tells Flash not to give up his ideals while fighting Savitar.
- Crazy-Prepared:
- A.R.G.U.S. has it set up so that their HQ is meta-proof and they have numerous fail-safes to ensure that unauthorised personnel cannot easily pass through security. And as it turns out even stealing the Dominator device triggers a fail-safe that locks any intruders inside the King Shark room and immediately sends security after them.
- As it turns out, having spent an eternity trapped inside the Speed Force, Savitar has found a way to crystalise the energy made from the Speed Bazooka into a solid form: The Philosopher's Stone.
- Curb-Stomp Battle: Savitar vs. Wally. Savitar No Sells all of Wally's punches and then breaks the poor kid's leg.
- Darkest Hour: Savitar murders Iris, and the one method they thought could defeat him—and is supposed to be triumphant in the original timeline in 2021—does absolutely nothing. Meanwhile, Savitar breaks Wally's legs, and Cisco is still battling Killer Frost in the forest...and things aren't looking too good for him either.
- Deus Exit Machina:
- Played with when Lyla inexplicably goes on a trip conveniently around the same time Team Flash pulls their caper. She never actually left, and she was actually anticipating that Barry will try something drastic to get the power cell. This might actually be a good thing, however, since surveying Barry's attempts to save Snart convinces Lyla to let them go free, and with the power cell.
- After Wally's Game-Breaking Injury, only Cisco remains as Barry's most powerful ally to fight Savitar. Then Cisco gets a vision of Killer Frost issuing a challenge and opted to fight her. Barry has no hard feelings though, and even tells Cisco to bring Caitlin back.
- Department of Redundancy Department: Joe describing A.R.G.U.S. as the most heavily-fortified structure in the history of fortified structures.
- Died in Your Arms Tonight: Iris to Barry's as foreshadowed since the winter finale.
- Digging Yourself Deeper: A dramatic example where Barry brings up Sarah Diggle when Lyla tells him why she can't trust him with the Dominator power cell.
- Do Not Call Me "Paul": Due to his status as a Time Remnant (or in his own words a "disposable hero"), Savitar hates being called Barry and breaks his Tranquil Fury mode when Joe tries to talk him down from killing Iris.
- Double Take: Snart takes another quick, baffled look at Grodd's cell when Barry matter-of-factly describes who it is to him.
- Downer Ending: Savitar successfully kills Iris.
- Dragon Hoard: A.R.G.U.S. is using King Shark to guard a Dominator power cell.
- Drama-Preserving Handicap: Normally, breaking into A.R.G.U.S. and stealing an item should be a piece of cake for speedsters who can additionally phase through walls. Except the walls are lined with equipment that dampens metahuman powers.
- Dude, Not Funny!: Team Flash treats Cisco's "Smart, Snart" joke as a Painful Rhyme.
- Easter Egg: One of the A.R.G.U.S. containment cells holds a prisoner listed as Cheetah.
- "Eureka!" Moment: When they learn that A.R.G.U.S. is heavily fortified and had power dampeners, Iris contemplates that it would take a "master thief" to break in. It occurs to Barry that he knows someone who fits that profile...
- Failed a Spot Check:
- In their efforts to complete the Speed Force Bazooka, Team Flash forgot one small but vital detail — it's built from the same technology that was already used to trap Savitar in the Speed Force in the first place, so Savitar knows exactly how to counter it.
- Barry, Cisco and Wally, the three people who have seen the vision of Savitar's murder of Iris, all don't seem to care when Iris wears the very outfit she's wearing during the (up until now) Flashforward.
- Fighting Your Friend: The Vibe vs. Killer Frost battle that has been foreshadowed all season happens, but the outcome is still undecided by the time the episode ends.
- Forced to Watch: Barry, Joe, and Tracy helplessly watch Iris gets Impaled with Extreme Prejudice.
- Foreshadowing:
- Early on, Snart lampshades the fact that the best-laid plans tend to go awry anyway. Guess what happens when they finally confront Savitar with the Speed Force Bazooka?
- After his grief over failing Team Flash, H.R.'s gaze lingers on Savitar's still-detached blade for a reason that will not be disclosed until the next episode.
- Likewise: as the plot of the second half of the season was progressing to this point, Barry's memory of the future altered slightly to show that H.R. was present the night Iris died. He was not present during the climax.
- Forgiven, but Not Forgotten: Lyla makes it clear though she's grateful to Barry for helping stop the Dominators, she hasn't forgotten that his time meddling is what brought them back to Earth; even though it's implied they would've done it sooner or later anyway. Later subverted when it's Barry's refusal to sacrifice Snart to save Iris that redeems him enough in her eyes to trust him with the power cell.
- Freeze-Frame Bonus: Savitar's old Flash costume has a faded emblem that distinguishes him from Barry.
- Friendship Moment: Snart and Flash share a genuine moment of friendship as they part ways.Captain Cold: "You see the good in me, I see the bad in you. Your goodness is your strength. And call me sentimental - I think the Flash should remain a hero."
- The Ghost:
- The Waverider is seen, but none of the Season 1 lineup of the Legends aside from Snart appear.
- Grodd's, Cupid's and Cheetah's cells (among others) are shown, but not the actual prisoners. We do at least hear Grodd roar as Barry and Snart pass by.
- For some reason Julian is completely absent from this episode without even a token explanation given.
- Godzilla Threshold: Barry teams up with Captain Cold (again) since he has no options left — and he does it by pulling Snart from the timeline. Fortunately for Barry, this doesn't backfire on him this time around.
- Go-Karting with Bowser: Snart believes an invite to the wedding will be his reward for helping with the caper and save Iris."Just don't put me at the singles table."
- Halfway Plot Switch: The energy source is obtained by Team Flash 75% through the episode. The final quarter deals with the fateful night predicted since the winter finale.
- Healing Factor: King Shark regenerates his severed hand (see An Arm and a Leg above) in a matter of seconds.
- Hero Antagonist: Barry has to break into ARGUS to get the power cell; Lyla doesn't trust Barry after Flashpoint. Subverted when she sees him refusing to sacrifice Snart to save Iris and gives it to him willingly.
- Hope Spot: Initially it looks like the Speed Force Bazooka is weakening Savitar and about to send him on a one-way ticket to the Speed Force. However, he quickly recovers, transforms the energy into the Philosopher's Stone, and then successfully kills Iris.
- History Repeats: An evil speedster once again kills one of Barry's loved ones. This is also the second time it happens in the penultimate episode of the season, both via impalement through the back while Barry is Forced to Watch. Iris' death also marks the second time the West family loses a female member.
- I Did What I Had to Do: Played straight with Barry when he travels back in time to recruit Snart despite time travel being the cause of their current predicament. Later subverted when he proves himself unwilling to leave Snart behind in King Shark's cell after obtaining the power cell. Of course, Barry might also be trying to avoid breaking the timeline even more, as Snart is destined to die at the Vanishing Point.
- Idiot Ball:
- Barry specifically told Team Flash not to tell him where Iris was hidden under any circumstances, since that would mean that Savitar would remember it. H.R. promptly violates this instruction the next time he sees Barry. Even worse, it was actually Savitar pretending to be Barry. You could maybe handwave it by saying that H.R. wasn't in the room when Barry specifically told everyone this information.
- It apparently occurs to absolutely no one that A.R.G.U.S.' power dampeners might possibly be useful against Savitar.
- Impaled with Extreme Prejudice: How Iris dies, as foreshadowed since the winter finale.
- Improbable Use of a Weapon: Snart uses the cell in his cold gun as an anesthetic to knock King Shark out.
- Internal Reveal:
- Tracy finds out that Barry is The Flash.
- The rest of Team Flash sans Jesse finally see the unmasked/unarmored Savitar.
- Snart finds out about Barry and Iris' engagement.
- It Only Works Once: Savitar reveals he has gained an immunity to the Speed Force Bazooka since it was used on him by Future Barry.
- It's All My Fault:
- H.R. blames himself for revealing Iris' location to Savitar to the point that he seriously questions why he is still a part of the team.
- Wally is left emotionally distraught over his inability to prevent Savitar from capturing Iris and tells Barry that he "let him down".
- Jerkass Ball: Lyla is at first totally okay with letting Iris die in order to punish Barry for Flashpoint. Thankfully, she comes around.
- Jerkass Has a Point: From an outsider's viewpoint, Lyla is completely right to not trust Barry after everything he did, good intentions or not.
- Leaning on the Fourth Wall: Snart comments that King Shark's cell reminds him of Jaws — and how they kept the shark offscreen to save money.
- Locked Out of the Loop:
- Barry asks Team Flash to hide Iris away from him without telling him her location. It fails because Savitar decides to disguise himself as Barry to find out her location.
- None of Team Flash lets Snart in on his fate with the Legends. Presumably, Snart himself never revealed most of his little side trip to the Legends. Apparently, neither did Gideon, as Barry meets (and later leaves) Snart right next to the Waverider, meaning Gideon should have spotted him.
- Manly Tears: Wally after failing to stop Savitar, and ultimately both Barry and Joe after Iris is killed. H.R. is also on the verge of this during his My God, What Have I Done? speech to Cisco.
- Master of Unlocking: Snart takes all but 35 seconds to break into A.R.G.U.S.' nuclear bomb-proof, identity check locked safe that cost 10 million dollars.
- Mood Whiplash: The majority of the episode is very hopeful and upbeat...until the Barry that returned to S.T.A.R. Labs reveals himself to be Savitar.
- Motive Rant: Savitar retells his reason for becoming the way he is to Caitlin.
- My God, What Have I Done?: H.R. is really down on himself for inadvertently telling Savitar where Iris was, to the point that he seriously begins to question his place on Team Flash.
- Mythology Gag:
- The title itself refers to Carmine Infantino, an iconic writer of the Flash during the Silver Age who created or co-created some of his most iconic Rogues, including Captain Cold.
- One of the imprisoned criminals at A.R.G.U.S is Cheetah, Wonder Woman's Arch-Enemy.
- Wally tormenting himself over the failure to protect Iris and imagining Barry getting disappointed in him, is a very important character arc for the Post-Crisis Wally West.
- Next Sunday A.D.: The episode takes place on May 23rd, 2017, exactly one week following this episode's original air date.
- Nice Job Breaking It, Hero: Savitar impersonates Barry to get into S.T.A.R. Labs and H.R. blabs Iris' location to him, which Barry specially asked he not know. Even if it wasn't Savitar, it would still have the same effect.
- Noodle Incident: Presumably at some point during the first season of Legends of Tomorrow, specifically between episodes 9-11, the Legends visited Siberia in 1892, though we never saw this in the series itself. Somehow Barry figures out that Snart is there.
- No One Gets Left Behind: Despite Barry claiming to do whatever it takes to save Iris, he proves himself unwilling to abandon Snart in King Shark's cell after obtaining the power cell. It's this action that redeems him in Lyla's eyes when they're caught by A.R.G.U.S. to not only release them, but also allow Barry to keep the power cell.
- No-Sell: Savitar does this to Wally's punches, Harry's and Joe's guns and in the end, also the Speed Force Bazooka.
- Not So Above It All: Perhaps because this is Snart post-Character Development, but he's a little more "loose" here than he was last time he and Barry met.
- The Oath-Breaker: Barry breaks his promise to never Time Travel again by plucking Snart during mid-Season 1 of Legends. Joe calls him out on it, but Barry retorts that "desperate times call for desperate measures".
- O.O.C. Is Serious Business: H.R. has a genuine Heroic BSoD after unwittingly blabbing Iris' whereabouts to Savitar, and Cisco had to give him a Get A Hold Of Yourself Man.
- The Place: Infantio Street is where Savitar kills Iris as noted by Killer Frost.
- Plot Hole: Despite A.R.G.U.S. HQ being installed with metahuman power dampener devices, King Shark is able to use his Healing Factor.
- Power Nullifier: A.R.G.U.S HQ is now equipped with metahuman dampener devices.
- Pre-Mortem One-Liner: Savitar, just before he kills Iris:Savitar: You lose, Barry.
- Product Placement: The Easter Egg regarding Cheetah is an obvious marketing strategy by DC and Warner Bros. to promote the upcoming Wonder Woman film.
- Recycled Plot:
- This isn't the first time Barry has gone to Captain Cold for help. This is noted by Cold. Fortunately, this time, Cold doesn't double-cross him.
- Barry pulls Captain Cold from the time stream to steal something, just like the Legion of Doom did. Of course Barry takes care to make sure the Cold he recruits is one who's already joined the Legends and reformed.
- Recruiting the Criminal: Barry recruits Cold to plan a heist.
- Removed Achilles' Heel: Savitar has developed an immunity to the Speed Force Bazooka after it was used on him in 2021, even converting the energy into the Philosopher's Stone.
- The Reveal: The Philospher's Stone is concentrated Speed Force energy created by the Speed Force Bazooka.
- Running Gag:
- The team just couldn't decide on what to call Tracy's weapon.
- Cold dropping shark-related pop culture references.
- Saved by Canon: Snart is this for the plot of this episode, given that Barry plucks him from before the events at the end of season one of Legends of Tomorrow. Ironic given that all the other characters are aware of his eventual fate.
- Shipper on Deck: He's under duress, but Snart tells Cisco that he'll put in a good word for Cisco with Lisa Snart if he opens King Shark's cell faster.
- Shooting Superman: Savitar's suit repels Harry's and Joe's shots without any trouble. Even aiming any kind of firearm at a speedster is a futile effort, as both of them should know by now.
- Shout-Out:
- Barry tells Cold that he needs his "particular set of skills".
Cold: Great movie.- H.R. pitches that they drop down to ARGUS in the style of Mission Improbable.
- The wavy beam trail from the Speed Force bazooka/gun/cannon look almost like the lasers from Photon Packs.
- A Simple Plan: Discussed:Snart: "There are only four rules you need to remember: Make the plan. Execute the plan. Expect the plan to go off the rails. Throw away the plan.”
- Skyward Scream: The ending shot after Iris is killed. Strangely, the scream is inaudible due to the dramatic background music playing.
- Stable Time Loop: The Philosopher's Stone was created by the energy from the Speed Force Bazooka.
- Stealth Pun: The title of the dramatic music that is playing when Savitar kills Iris is literally "Murder Song". It's sang by AURORA.
- Storming the Castle: Much of the episode is about Barry and Snart infiltrating A.R.G.U.S. HQ.
- Talking the Monster to Death: Joe tries to do this to Savitar when he comes for Iris by pointing out that, at one point in time, he used to be his son. Unfortunately it doesn't work since, as a Time Remnant, Savitar was never technically the "real" Barry to begin with and hates being referred to as Barry.
- That Man Is Dead: Savitar makes it clear once again that he doesn't respond to his old name anymore.
- Timed Mission: Team Flash has less than 24 hours to complete the Speedforce Bazooka/Cannon as Iris is fated to die by the end of the day.
- Token Human: Cupid among the incarcerated criminals at A.R.G.U.S. Her cellmates are Cheetah (self explanatory), Grodd (gorilla) , and King Shark (self explanatory)
- Took a Level in Badass: Barry has learned basic CQC in case he has to fight while his Super-Speed is compromised.
- Unexpected Character:
- Captain Cold. Most of the hype surrounding him this season was him being a member of the Legion of Doom on Legends of Tomorrow (and that arc ended with him being put back in his timeline on his path to be a hero), with no hint he'd be back on his parent show.
- Harry as well. Unlike with Captain Cold, he wasn't shown in the previews, and since he's played by the same actor as H.R., even looking at the guest list ahead of time wouldn't have helped deduce his appearance.
- The Unreveal: Barry and Snart go through three security checks at ARGUS' entrance: an ID card check, then an eye scan, and word association. It's never elaborated what the association actually was, as well as if there are any other security checks after that.
- Unwitting Instigator of Doom: H.R. telling "Barry" of Iris' hiding place, much to his horror.
- Unspoken Plan Guarantee: Cruelly subverted. Barry tells his team that he can't know of their plan to stop Savitar because then Savitar will remember it as well. Because Barry doesn't know, neither does the audience...and it still fails.
- Video Will: After sending Barry to fetch caviar at the beginning of the episode, Iris prepares one with her phone. The video is played (to the audience, not to the characters, yet), showing her reciting what should be her wedding vows.
- Villain Ball: Savitar's Ripple-Proof Memory allows him to "remember" Barry recruiting Cold but he brushes it off as he's that self-assured about his future victory. He's not unjustified.
- Wham Episode: The fated night comes to pass, and Savitar successfully murders Iris.
- Wham Shot:
- After the caper at A.R.G.U.S., Barry speeds back to S.T.A.R. Labs and reports it a success. When H.R. answers his question of Iris' whereabouts, Barry turns around, revealing himself to be Savitar.
- When Barry fires a successful shot from the Speed Force Bazooka at Savitar, it at first looks like it's working and he'll be re-imprisoned in the Speed Force...but then he effortlessly shrugs the blast off.
- What Kind of Lame Power Is Heart, Anyway?: H.R. has a moment of this, noting that Team Flash has given him a home, a purpose, even a Love Interest...and all he's given them in return is coffee, mediocre drumming, and running commentary. Cisco tells him that he's been reliable and helpful, even if it's not so obvious.
- What the Hell, Hero?: Barry gets one from Joe and Iris about time traveling to the past to recruit Snart as it was his previous meddlings with time that created their current crisis in the first place.
- The Worf Barrage: Despite the sheer effort Team Flash puts into making it, the Speed Force Bazooka ultimately proves to be futile against Savitar, and if anything makes him more powerful by giving him the Philosopher's Stone.
- Would Hit a Girl: Played for Drama. This episode is the fated night of both Iris' death and Cisco's battle with Killer Frost.
- You Are Better Than You Think You Are:
- As Barry drops Snart off back in time where he got him from, Snart advices Barry that he should stop trying to beat Savitar at his own game by being ruthless like him, telling him his goodness is his strength and he thinks Flash should stay a hero.
- After H.R. beats himself up over giving up Iris' location to Savitar, Cisco tries to console him by saying it could have happened to anybody of them. It doesn't work.
- You Can't Fight Fate: Despite everyone's attempts to avert this for the past five months, Iris is ultimately killed by Savitar, as first foreseen by Barry in the midseason finale.
