Plot hole: In Aunty Em's Emporium, when Medusa turns the older woman to stone, she has hold of Annabeth's wrist and Annabeth cannot free herself. Grover comes along later, as Percy is keeping Medusa busy, and breaks the arm of the statue that is holding Annabeth (near the elbow). Annabeth is able to easily pry the statue's severed arm's grip from her wrist, even though the fingers and thumb weren't broken at all, meaning she could have easily freed herself at any time.
Plot hole: Luke states that the reason for hiding Zeus' lightning bolt in Percy's shield is so that he can get the bolt to Hades, and thus start a war that will wipe out the Gods of Olympus. However, this simply cannot work. The whole plot of the movie rests on Percy accidentally dropping the shield, which Percy did innocently and not by any kind of design or planning. Had he not dropped the shield, Percy and the others would have been taken by the souls, Hades would never have discovered the lightning bolt, and the plot of the movie unravels from there.
Answer: At some point in her relationship with Poseidon, he told her about the elevator. Otherwise, she could not have known.
raywest ★