Continuity mistake: When Hephaestus is hammering the lightning bolt on the table, the position of the bolt changes between shots.
Continuity mistake: Between shots of Zeus saying "I swear Hades, when I get out of here," the mountain of molten lave he is trapped in rises further up his body.
Continuity mistake: After Meg's death the nearby rocks and objects change between shots.
Continuity mistake: In the beginning, only four titans are imprisoned underground. Later, as Hades sets them free, the arms of five different titans burst out of the ground.
Continuity mistake: Panic flies up in the air & lands with his horns stuck in Pain's butt. When he lands, he has a horn in each cheek. Then Pain stands up & turns sideways, showing Panic with both horns in only one of Pain's cheeks.
Continuity mistake: One of Herc's shoulder clasps come undone during the Cyclop's fight. After the Cyclops drops him into the cart, the clasp is done up again.
Continuity mistake: In the scene where young Hercules is pulling the cart of hay, his's adopted father and the donkey are riding on the seat and both are holding onto the sides of the seat since they're going so fast. Once they stop, Hercules's adapted father mentions the donkey's hurt foot, and she's now got a sling on the left front leg which wasn't there during the wild ride.
Continuity mistake: When Pain and Panic are shown for the first time, the cracks on the ground change between shots.