Corrected entry: In the scene where Percy and his friends are fighting the Hydra, Percy begins to wildly swing his sword to cut of their heads. At one point, he slices off the middle head which breathes fire, and it grows back. This is incorrect as the middle fire breathing head cannot be chopped off.
Grumpy Scot
Corrected entry: When Medusa first notices Percy she puts her glasses on the crazy lady's statue, but when they are later seen with the head she has glasses on.
Correction: Well yeah, one of them put the glasses on the head to make it safer to carry around.
Correction: According to who? The movie takes some liberties with established myth.
Grumpy Scot