Revealing mistake: When Elsa is waiting in the lobby, she's wearing a dress which shows her normal, not wooden legs. It's very apparent when she is crying on the floor.
Continuity mistake: When Josh has got out and they go looking for him, they find Aiden on a small bridge. From a distance he's got a very dark sweat stain on his shirt. In a closer shot it's faded to nearly nothing, and gets lighter/darker in different shots throughout the scene.