Narcissus is not a Greek God, and therefore would not be on Mount Olympus. Zeus freed the Cyclops along with Giants and creatures called Hundred-Handed Ones, and he was given the gift of thunder and lightning as a token of appreciation. The Titans say Zeus put them there, but Zeus's grandfather Uranus did. The Cyclops, although brother to the Titans, was not a Titan.
In the movie, Hades releases the Titans from a place at the bottom of the ocean, but in the original myth they were banished to Tartarus, which is in the deepest and worst section of the underworld. Zeus did not bestow the underworld on Hades but the two, along with Poseidon, drew lots. Pegasus was created by the blood of Medusa, not clouds (as seen in the film) on Olympus. The Graeae, perpetually old women who helped Perseus find Medusa, shared an eye. In the movie, Alcmene and her husband adopt Baby Hercules. Zeus' wife Hera, furious over her husband's adultery, swore vengeance, and bestowed misfortune over Hercules wherever and whenever she could. Hercules was conceived when Zeus disguised himself as Alcmene's husband Amphitryon, who was away to fight in a war. While Zeus was his father, his mother was a mortal named Alcmene, which made him a demigod. There are many differences between the film and the original myths.
