!!The 1981 film

* ExecutiveMeddling: The original script had more FamilyUnfriendlyViolence and more nudity on the part of Andromeda (she was supposed to remain nude throughout the entire Kraken sacrifice scene). These elements were toned down in pre-production when the British censors reviewed the script and told the studio that they would give the film an "AA" (no one 14 and under admitted) rating if they put those scenes in the film.
* MoneyDearBoy: Part of the reason LaurenceOlivier was cast as Zeus. Probably the same with Maggie Smith.

!!The remake:

* CastingGag: The original featured Bond girl Ursula Andress playing Aphrodite. The remake also features a Bond girl, this time Gemma Arterton playing Io.
* CreatorBacklash: Louis Leterrier disowned the final film, claiming "it's not my movie" and refused to return for the sequel.
* DeletedRole: Apollo and Athena had major roles in the original cut, but the film was reworked. Apollo's role was heavily reduced, while Athena was almost cut completely. Additionally all the Gods originally had lines in the first scene on Olympus.
* OldShame: Creator/AlexanderSiddig, who played Hermes, referred to this as "the lamest movie I ever made", claiming 50% of his performance was deleted.
* SoMyKidsCanWatch: Creator/LiamNeeson took on the role of Zeus because his sons thought it would be awesome.
* StarDerailingRole: For both Sam Worthington and post-production 3D conversions in general.
* WhatCouldHaveBeen:
** Matthew Belamy was writing the score, but had to abandon midway through as Music/{{Muse}} started a tour.
** As detailed [[http://www.chud.com/23299/by-zeus-the-version-of-clash-of-the-titans-you-didnt-see/ here]], the film's original story was drastically different:
*** Perseus and Io's relationship was purely platonic; with a romance developing between him and Andromeda during his time in Argos. It would have ended with a MaybeEverAfter situation between them.
*** Perseus's main motivation for going after the Gods in the original was to show that mankind did not need to rely on them for anything. Likewise he wished to save Andromeda because he felt that nobody should be sacrificed for the sake of the people. In the finished film, he just wants revenge on Hades.
*** Apollo and Athena had major roles, conspiring against Zeus and Hades. Apollo was originally the one who offered Perseus passage onto Olympus.
** Zeus was far more villainous in the original cut. The film would have ended with Perseus going to Olympus and putting Zeus and the rest of the Gods on notice. Zeus would offer him a seat, but Perseus would refuse - saying his father is a dead fisherman.
** The original idea for the movie was a CrossoverCosmology with [[Myth/MesopotamianMythology Tiamat]] waging war against the Greek pantheon and Perseus being assisted by [[Myth/EgyptianMythology Thoth, Osiris]], [[Myth/MesopotamianMythology Marduk]] and [[Literature/TheBible Yahweh]]. He would also apparently have a romantic affair with some "Cthonian Earth goddess." (The filmmakers apparently have something against Andromeda for some reason...)

!!Wrath of the Titans

* ActorAllusion:
** Not only does Hephasteus sound a bit like [[PiratesOfTheCaribbean Davy Jones]], but has the scraggly beard from human!Jones and even says "release the kraken" at one point (in reference to the first film).
** At the end, Zeus is basically using [[ThePhantomMenace the Force]] on the Makhai [[spoiler:and Force Lightning against Kronos!]]
* CastingGag: Yet another Bond Girl joins the cast, this time Rosamund Pike from ''Film/DieAnotherDay''.
* TheOtherDarrin: Creator/RosamundPike replaces Creator/AlexaDavalos as Andromeda. Also Ares was a minor background character in the first film, played by Tamer Hassan. In this sequel where he has a larger role, he's played by Edgar Ramirez.
* PlayingGertrude: Zeus is meant to be Hephaestus's father. Bill Nighy is three years ''older'' than Liam Neeson.
* WhatCouldHaveBeen:
** Gemma Arterton was slated to return as Io, but was busy with ''Film/HanselAndGretelWitchHunters'', and they opted to just kill of Io rather than recast her too.
** Javier Bardem was considered for Ares, and James Franco for Agenor.