Jesse returns to Earth 1 and alerts Team Flash that Harry has been abducted by Grodd, leading Barry and Cisco to return to Earth 2, with Caitlin and Julian in tow in an attempt to rescue Harry from Gorilla City. Meanwhile Jesse considers staying on Earth-1 to finally pursue a relationship with Wally.
- Actor Allusion: The episode has Tom Felton going up against sentient apes. The episode even has Julian Squeeing over Planet of the Apes.
- Adaptational Villainy: Traditionally, Grodd is the Token Evil Teammate amongst the Gorillas who want to subjugate humanity and Solovar is usually an ally to the heroes trying to stop him. Here the roles are reversed. Subverted when it turns out that it was all a ruse by Grodd to stage a coup so he could conquer Earth-1. Nonetheless, Solovar is still not the most pleasant of individuals.
- Adventurer Outfit: Julian dresses up much like Indiana Jones for the trip to Earth-2, and even lampshades it, calling it "the perfect attire".
- Ambiguously Evil: Solovar, as we don't know if he's just being overprotective of his people, or is really as nasty as he shows.
- Antagonist Title: The sentient gorillas are this episode's villains.
- Arch-Enemy: As the fourth most recurring villain of the series, Grodd is just about ready to join the ranks of the other entities that shared the title of the Flash's nemesis: Captain Cold, Zoom and the Reverse-Flash.
- Artistic License – Gun Safety: Julian responds to objections over him joining the rescue operation by pointing out that he is armed. This involves him unnecessarily pulling his handgun from its holster (rather than just revealing its presence) and holding it with his finger on the trigger.
- Asskicking Leads to Leadership: This is how leadership works in Gorilla City; thus, Solovar is the leader, being the strongest gorilla. Once Barry defeats him in battle, the gorillas no longer respect Solovar, and instead turn to follow Grodd. Grodd had hoped that Barry would kill Solovar, but the results are effectively the same either way.
- Bad "Bad Acting": Caitlin pretending to be upset while trying to explain Barry's "death" to Grodd.
- Batman Grabs a Gun: Barry is adamant on on not killing Solovar, but when he's about to lose the fight with Solovar he ultimately ends up using the one technique that's thus far only been used by evil speedsters: the vibrating hand. Fortunately, it doesn't kill Solovar.
- Broken Pedestal: Caitlin's fears back in Season 2 are proven true: that Grodd has apparently lost his soft spot for her.
- The Bus Came Back: Not just Harry and Jesse (the latter who already showed up in the last episode's cliffhanger), but, if the title didn't already clue you in, Grodd, which makes him the first recurring villain from Season One to come back this season (not counting (semi)reformed Heatwave in 'Invasion!'). And in the very final minute, Gypsy is revealed to be under Grodd's control.
- Can't Kill You, Still Need You: Grodd has no intention of killing Cisco, yet, as he still needs him to open the breaches to Earth-1.
- Celebrity Paradox: Julian thinks that Earth-2 is a Planet of the Apes-like world when Barry mentions Team Flash is gonna rescue a friend (Harry) from sentient gorillas. Tom Felton was in Rise of the Planet of the Apes.
- Chekhov's Gun: Averted. Julian shows that he's carrying a gun, but it's not used in this episode.
- The Chessmaster: Grodd was taught to always think ahead by his "father".
- Chewing the Scenery: Both Harry and Cisco when Grodd speaks through them.
- Continuity Nod:
- The team remember Grodd invaded Earth-1 as one of the future headlines from the night that Iris died.
- Caitlin states that she should join in on the rescue reminding everyone of Grodd's affection for her.
- Caitlin also remembers that it was on Earth-2 she met Killer Frost.
- After learning of Caitlin's ice powers, Harry points out he never believed that he and Cisco were the ones that released Barry from Mirror Master's mirror.
- Wally brings up Joe's abduction by Zoom when assuring his understanding to how Jesse felt during Harry's kidnapping by Grodd.
- Julian brings up his past experience as an archeologist to Team Flash so they could have a reason to let him join in the rescue mission.
- Crazy-Prepared: Grodd. He had a back up plan in case Team Flash escaped - a brainwashed Gypsy.
- Does This Remind You of Anything?: Before leaving for Earth-2, Barry tells Wally that to spend some time while they're gone he should "show off" to Jesse. The first thing Wally shows off is to vibrate his hand.
- "Eureka!" Moment:
- During the arena battle when Julian mentions reversal Cisco realizes that Flash needs to "pull a Reverse-Flash" to defeat Solovar.
- Barry taking Cisco's idea of someone among them dying so the rest can escape, just not the same way Cisco thought.
- Event Title: The attack in the title refers to Team Flash charging towards Gorilla City to rescue Harry.
- Evil Chancellor: Grodd appears to be this to Solovar, and true to form with this trope, manages to fully usurp the position as leader by the story's end, thanks to The Flash's help.
- Faking the Dead: How Barry tricks Grodd into taking him out of the Power Nullifier cell. To make it more convincing, Caitlin uses her freezing powers to lower Barry's body temperature.
- Forgot About His Powers: If Grodd had just read everybodys mind, he would have known Barry was just Faking the Dead. Hell, he could have just forced Cisco to open a breach for him and be done with it.
- Heroic Sacrifice: Cisco is willing to lay down his life to prevent Grodd from being able to open the breaches to Earth-1.
- Idiot Ball: Grodd is fooled when Barry pretends to be dead, so he takes his "lifeless" body outside of the cell and just puts it there, and leaves. It's true that Grodd couldn't have known about Caitlin's powers being used to complete the deception, but on the other hand he does have telepathic powers, so it wouldn't be too difficult for him to check whether Barry's brains are still working.
- I Lied: Turns out Grodd is the one who wants to conquer Central City, despite him promising that he would spare it.
- I'm Standing Right Here: Barry and Iris' discussion on keeping Wally in line...Joe: You do know Wally can hear you.
(cue a dumbfounded and insulted Wally glaring at the two of them)
Barry: Sorry Wally! - Instant Sedation: The Tranquilizer Darts that hit Team Flash have them out within seconds, even Barry who due to his metabolism should be especially resistant to them or at least recover faster than the rest of the team. Then again, Grodd's Crazy-Prepared so he surely considered this when setting up the trap.
- Internal Reveal:
- Joe learns that Caitlin, Harry and Barry had sent Grodd to Earth-2's Gorilla City.
- Jesse discovers that Wally is a speedster.
- Harry learns that Caitlin is a Meta, H.R. isn't a scientist and about the Headlines the Team are trying to avert.
- Irony: Grodd says that "father taught me well" while he's possessing someone who looks just like his "father".
- It's Not You, It's My Enemies: Caitlin warns Julian about being with her because she is still fearing her evil side.
- Jumped at the Call: When Julian learns that the team is visiting another Earth, he immediately joins them.
- Kick the Dog: Grodd has Barry shot with a tranquilizer when Barry attempts to introduce compassion to Gorilla City, and later reveals he has no intention of letting him, Cisco, Harry, Julian, or even Caitlin go despite winning the duel.
- Lured into a Trap: Everything Grodd does is this—he lures Harry into Gorilla City as bait to get The Flash and Cisco into Gorilla City, knowing that they could get rid of Solovar and open the breach to Earth-1, allowing Grodd to invade.
- Manipulative Bastard: Grodd engineers the downfall of Solovar and his own rise to power by having Flash defeat him under false pretenses.
- A Man Is Always Eager: Barry has a certain idea of how to celebrate the victory against Grodd with Iris.Iris: So no more nightmares? You finally gonna get some sleep tonight?
Barry: (playfully) Well that last part is entirely up to you! - Might Makes Right: Solovar's the most powerful gorilla (Grodd even admits he can't defeat him), and he'll stay Gorilla City's leader as long as he continues proving himself strong enough to fight any threat.
- Misplaced Vegetation: Cisco comments about the weirdness of Earth-2 Africa having a rainforest.
- Moment Killer: Wally and Jesse are marginally annoyed to discover that H.R. has been spying on their intimate moment.
- Morality Pet: Averted, Grodd acts as if Caitlin is his, stating her as the reason to trust he will let Team Flash go if Barry wins the duel against Solovar, yet reneges on his promise after Barry wins in the arena.
- Mythology Gag: Julian makes an excuse to Captain Singh about him and Barry going to a convention in Bludhaven.
- Never Trust a Trailer: The official previews for this episode stated that Jesse and Wally would stay on Earth-1 to stop a metahuman that can control gravity. While they do end up staying on Earth-1, such a character does not appear at all.
- Nice Job Breaking It, Hero: Team Flash's attempts to stop the future Gorilla attack backfires on them.
- No Good Deed Goes Unpunished:
- While the intention was that sending Grodd to Gorilla City would grant him comradery among his own kind, Team Flash finds their actions have made them pawns in a coup for power.
- Barry spares Solovar's life to try and prove to the gorillas that humans aren't evil and only want peace. However, they still end up fearing humans due to Barry defeating Solovar to begin with, leaving them ripe for Grodd's manipulations.
- Not So Above It All: The very stuffy Julian gets very excited over the idea of visiting a parallel Earth with talking apes - heck even digs out his own archeologist gear for the occasion, complete with a gun.
- Obscured Special Effects: Grodd mostly speaks through Harry and Cisco while he himself remains offscreen. It's pretty obvious that this done to reduce the amount of shots featuring Grodd, thus saving the money required to animate a fully computer-generated gorilla for those shots.
- Once a Season: Just like in season 2, the 13th and 14th episodes form a two-parter about travelling to Earth-2 on a rescue mission for a Wells. However, this time the situation is reversed between Harry and Jesse.
- More broadly speaking, the 13th and 14th episodes of the first season also were a two-parter.
- This is the third time in as many seasons that Team Flash are dealing with Grodd.
- Other Me Annoys Me: Harry's reaction to H.R.
- Out of Focus: Given that this half of the season was geared towards Barry doing everything in his power to save her, Iris, while still featured, and her ongoing fates presence is felt on Earth-2, with a side mission to prevent Grodd's attack on Earth-1's Central City as the Future Newsline read, Iris is barely in on the action this episode, acting mainly as a supportive big sister towards Wally.
- Passing the Torch: Barry leaves Central City under the protection of Kid Flash and Jesse Quick while he's gone.
- Person as Verb: Barry defeats Solovar by “pulling a Reverse Flash” and doing a vibrating punch.
- The Place: The title refers to Grodd and the other sentient gorillas' home in Earth-2.
- Power Nullifier: Flash and company are kept in cells that contain Barry and Cisco's powers, so, while they still have their abilities, they can't use them to break free.
- Psychic Powers: We already know that Grodd possesses them, but what's surprising is that somehow Solovar also seems to have them. It's unknown if the other gorillas have these powers as well, or if it's just Grodd and Solovar.
- Rescue Arc: The episode revolves around Team Flash embarking on a rescue mission to save Harry.
- Revenge: Grodd reveals this as his main motivation for attacking Central City—to get revenge on The Flash for banishing him to another world.
- Self-Fulfilling Prophecy: Subverted. It initially seems as if Barry's attempt to stop the future gorilla attack on Central City is what ends up causing it in the first place. However, they all escape Earth-2 before Grodd can use Cisco's power to open the breach and Grodd just ends up using Gypsy's power instead, so presumably the invasion would have happened anyway with or without the rescue mission, and at least now the heroes have a brilliant mind like Harry to assist them in their defense.
- Ship Tease: Caitlin and Julian fully realize their attraction, and despite her hesitance, given the dangers her powers present against him, he merely invites her out to dinner.
- Shipper on Deck: Iris, Joe and H.R. are on board for a Wally and Jesse pairing and H.R. actually manages to convince Jesse to stay on Earth-1.
- Shockwave Stomp: Solovar during the fight with Barry, so much that in engulfes the entire arena and stops Barry in his tracks.
- Shout-Out:
- Julian mistakes that Barry, Cisco and Caitlin are headed to the "Planet of the Apes," which Barry corrects him that it's only "The City of the Apes."
- Referencing the same work, Cisco ruefully notes that Grodd had Barry do his "damn dirty work".
- When first meeting Julian, Harry refers to him as "Indiana."
- Barry and Solovar's Trial by Combat gives a giant Homage to the Spartacus series, from the camera angle showing the arena, to the fighting choreography being done in slow motion.
- Cisco mentions that they sent Grodd to Gorilla City "when he went after Fay Wray here."
- Upon arriving in Eart-2, Cisco says "Welcome to the Jungle, Baby."
- Julian mistakes that Barry, Cisco and Caitlin are headed to the "Planet of the Apes," which Barry corrects him that it's only "The City of the Apes."
- Spoiled by the Format: It seems that the heroes wrap everything up in the end...but then you remember that this is a two-part event, and that Jessica Camacho is listed in the opening credits as Gypsy...so it's easy to guess what will happen in the end.
- Spoiler Opening: Oddly enough, the Previously on… clipshow after the Opening Narration does not feature the episodes with Grodd. What does get through are clips from Gypsy's episode, foreshadowing her return.
- The Stinger: Grodd is still planning on invading Earth-1, and he has his own Breacher to takes Cisco's place: Gypsy.
- Tempting Fate: Barry is quick to assure Iris that he and the others were able to stop Grodd's attack on Central City, striking off another event off the list of future Headlines. Meanwhile at the same time on Earth-2, Grodd is still ready to begin his trip across dimensions, with his own breacher, Gypsy, ready to facilitate the invasion.
- Thou Shalt Not Kill: Grodd urges Barry to kill Solovar, but Barry insists he will win the fight without murder. He does end up finally using the vibrating hand technique, but it doesn't kill Solovar. Though, even with Solovar alive, Grodd still ends up winning anyway.
- Tranquilizer Dart: Used to subdue Team Flash as they approach Gorilla City. And then later used to subdue Barry after he defeats Solovar.
- Trial by Combat: Solovar promises to release Flash's group if he can defeat him in a gladiatorial combat.
- Unexpected Character: Yes she appears briefly in the episodes recap prologue, but even still given she only appears at the very last seconds, it wouldn't be remiss to find Gypsy under Grodd's control a slight shocking.
- Ungrateful Bastard: Grodd. His second appearance had him trying to create more apes like him, so Team Flash sent him to Gorilla City so he could be with others like him. But Grodd doesn't see it that way. He sees it has his home being taken from him even though he was forced to skulk in sewers and empty skyscrapers on Earth-1.
- Wham Shot: A mind controlled Gypsy is now a tool for Grodd's escape.
- What the Hell, Hero?:
- A minor version, but when Jesse mistakes H.R. for Harry, and later H.R. innocently jokes that he isn't just her father's replacement, but his improvement, Cisco informs H.R. that Harry has been kidnapped, H.R. immediately apologizes for his insensitivity, which Jesse accepts.
H.R.: (to Jesse): I'm sorry I took the smile from your face.- Caitlin gives a slight one to Julian when she suspects he only came to Earth-2 in an effort to protect her.
- You Are Better Than You Think You Are:
- Wally assures Jesse, to limited success, that he didn't just like her just for her speed as she feared.
- Despite her fears of hurting him with her powers, Julian has no fear of her, and merely wants to be with Caitlin.
- You Can't Fight Fate: Grodd is still invading Central City, thus Barry's efforts to stop another incident connected to Iris' death failed.
- Your Princess Is in Another Castle!: The episode ends with the heroes thinking they have thwarted Grodd. However, it is only a minor setback since Grodd has a backup plan.
