As a Studio TRIGGER related anime, there will undoubtedly be many shoutouts to other sources.
Episode 1
- It applies to the series as a whole, but the two pilots needing to be in sync and balanced brings in to mind the Pacific Rim franchise; where the two Jaeger pilots need to be Drift compatible to move their Jaeger. The fact that the pilots in the sequel are teenagers/cadets further strengthens this reference.
- Also applying to the entire series, the plot about students working mechas in different sex pairs through their psychosexual energy to fight against aliens (who are also related to the male lead's female partner) brings to mind De:vadasy, an obscure 2000 videogame and OVA series.
- The FranXX themselves have been compared to the mecha in Star Driver (for the designs), Neon Genesis Evangelion, Godannar and The Five Star Stories (when it comes to how they function and the symbolism that comes with it).
- Strelizia's transformation looks a lot like Ryuko Matoi's.
- Zero Two seems to be an amalgam of Haruko, Nonon, Asuka, Lum, and Star.
- Zero Two's cap, and the jaunty angle she wears it, is remarkably similar to Joseph Joestar's hat.
- The plantation is shown to have a number of long escalators, similar to NERV headquarters.
- Pre-transformation, Strelizia's animal form looks like the robotic lions from Zoids. Alternatively, it could be yet another Evangelion reference, since it resembles the cat-like Beast Mode of (what else?) Unit 02. It also bears a slight similarity to the Pokémon Solgaleo.
Episode 2
- The council that oversees all operations bear similarities to SEELE, in the same vein, the underground city seen in through the elevator's window is akin to a mix of the Geofront and Tokyo-03.
- Hiro's "Move! Move!" moment in the Franxx is a direct copy of Shinji's scene under the similar circumstances in Episode 19.
Episode 3
Episode 4
- Mitsuru's bandages resemble those of Rei in Episode 1-2 of Neon Genesis Evangelion.
- Hiro and Zero Two's destruction of the worm bore great resemblance to Tengen Toppa Gurren Lagann action scenes, including Hiro having the same motions as Simon during the fight. Emerging from the worm brings to mind the Giga Drill Break and Sen-I-Soshitsu.
Episode 5
Episode 6
- The franxx's launch sequence, especially the way the various gates open is quite similar to the EVA's launch sequence (minus being carried by elevators to Tokyo-03).
- The wings Strelizia gains at the end of the episode look and move a lot like the Wings of Light, albeit in a different color. They are also almost the same shape as the wings from the awakened EVA 01 during End of Evangelion.
- The whole episode feels similar to episode 8 of Tengen Toppa Gurren Lagann. It's a major battle taking the entire episode that concludes with a character having to come back from near death to help snap their partner out of their Heroic BSoD. Only in this case, Hiro lives while Kamina died.
- Zero Two's failed attempt to fight against the Klaxosaur after Hiro is put out of commission is highly reminiscent of Asuka's "I'll Kill You" moment against the Mass Production Evangelions.
Episode 7
- Turns out the tumor that was killing Hiro in the previous episode left a scar shaped like a 4-pointed star. 4-pointed stars have shown up in many anime by Studio TRIGGER before. Particular note to Kiznaiver, where the main cast had similar scars.
Episode 8
- The Klaxosaur burning the girls' suits with his blood is similar to the 9th Angel, Matarael, from Neon Genesis Evangelion, who used acid to destroy NERV's defences.
Episode 9
- In another Neon Genesis Evangelion reference, Goro remains blocked inside a humongous monster like it happened to Shinji in episode 16, without much oxygen and unable to move. Similarly, the Klaxosaur is destroyed from the inside, in a death similar to Leliel's.
Episode 10
- The plantation culture is reminiscent of Brave New World.
Episode 11
- Kokoro seems to reference Kamina's 'Believe in the person who believes in you' speech.
Episode 12
- A few shots
make for some pretty cool cinematic parallels with "End of Evangelion". - One of the books from the flashback is James G. Frazer's The Golden Bough, once a seminal work on comparative religion, whose theories are echoed by several elements of the series.
Episode 13
- Little Zero Two kind of looks like a younger Sucy with red skin and horns.
- The nurse who takes care of a young Zero Two looks strikingly similar to the Anti-Spiral.
- The picture book's story is a Gender Flipped version of Beauty and the Beast, though the plot is more reminiscent of The Little Mermaid.
Episode 14
- Just like the comparison in 13, like in Beauty and the Beast, the girl leaves to return to her Papa, leaving the guy in a dark depression.
Episode 15
- The final blow against the mountain-sized Klaxosaur is compared with Tengen Toppa Gurren Lagann. The even larger giant hand in the aftermath invites comparison even more so!
- The remnants of Plantation 13 resembles Yggdrasil from Little Witch Academia (2017)
Episode 16
Episode 17
Episode 18
- Kokoro's dress is made from curtains, just like Scarlet O'Hara's in Gone with the Wind.
Episode 19
- Several scenes in this episode is a massive shout out to Evangelion, especially Werner's backstory, which parallels Gendou, & Karina Milse's demise during FranXX unit's test, which parallels Yui Ikari's.
- The motion tracker APE’s security detail uses when entering the Klaxosaur Princess’s lair is very similar to the ones used by the Colonial Marines in Aliens.
Episode 20
- The entire episode has one to Tengen Toppa Gurren Lagann's mid season plot twist along with SEELE's original motivation back in Evangelion, namely, The Klaxo-sapiens were the previous defenders of Earth, much like Lordgenome's generation, who fought against the VIRM, an alien race that seeks to induce Instrumentality on others species either by manipulation or force, much like SEELE did in Evangelion and End of Evangelion.
- Going back even further, an alien species that tricks humanity into attacking Earth's defenders as a long term plan to avenge a defeat in the time of the dinosaurs is the plot of Getter Robo Armageddon.
Episode 21
- The start of the episode is one to Evangelion and End of Evangelion Instrumentality / Third Impact ascended all the adults into goo.
- Delta and Epsilon meet their end in a manner similar to Asuka's in End of Evangelion, which is: ripped to pieces and eaten; the way that the VIRM automaton destroys their cockpit by devouring it on the other hand is also one to Bardiel's destruction in Rebuild of Evangelion.
Episode 22
- The EVA and Gurren Lagann parallels continue, with the final battle being in space
Episode 23
- The reunion scene between Hiro and Zero Two in the Strelizia Apus seems right at home with the original Episode 26 from Neon Genesis Evangelion, as it is loaded with Limited Animation. The scene goes as far as depicting Hiro as his poorly hand-drawn Prince and Zero Two as a simplified drawing of her child self.
- The Strelizia's True Apus form is practically Buster Machine No. 7's sister, since the Franxx transforms into a mecha version of Zero Two.
Episode 24
- The final battle against VIRM is very much out of the Studio Gainax mecha playbook: GunBuster, Neon Genesis Evangelion, and Tengen Toppa Gurren Lagann are all referenced.
- The souls of Zero Two and Hiro returning to earth after centuries looks just like the end of GunBuster.
