The trivia items below may give away important plot points.
Hades claims that when a god dies, there isn't death, just nothing and oblivion (despite human beings, from which souls travel to the Afterlife of the land of the dead). It's confirmed when Poseidon, Ares, and Zeus die, showing them as magical golden sand vanishing into the air. Since then, Cronos is revealed to be a giant composed by rock, lava, and fire, it implies that Cronos created Olympian gods using the rock, lava, and fire of his own incandescent body, giving them life, but not a soul, to guarantee an existence in the Afterlife, missing in nothing.
A sequel for the film, titled "Revenge of the Titans" was in production, and the plot would have involved the resurrection of the gods. However, it was later scrapped, due to the poor reception of this film.
Following the release of this film, a sequel called "Revenge of the Titans" was planned. The plot would have involved the resurrection of the Olympians. However, possibly due to the poor reception of the film, it was later scrapped.