Gemma Arterton was originally supposed to return, but scheduling conflicts with Hansel (2013) prevented that. Her character was written out, rather than being re-cast, as Andromeda was.
The movie takes place 10 years after the previous one.
Bill Nighy, who plays Hephaestus, when recognizing Perseus, says "Release the Kraken". Nighy plays "Davy Jones" in Pirates of the Caribbean: Dead Man's Chest (2006) and says the same thing.
Contenders for the role of Andromeda were Hayley Atwell, Georgina Haig, Janet Montgomery, Dominique McElligott, and Clémence Poésy. The role was previously portrayed in Clash of the Titans (2010) by Alexa Davalos, who turned down an offer to reprise it.