Continuity mistake: In the scene where the guy and the girl are making out on the bed, they trigger a bell to ring in Kane's lair. The bell shown ringing is a large bell on the far left top row of two rows of bells. When he walks into the room to see which bell is ringing, the bell ringing is a small bell in the middle of the bottom row and the large bell isn't moving at all. Later in the movie, that same large bell is triggered when the kids are walking down the hall and hit a trip wire, and it makes a completely different sound than the first time.Rochelle McCarty
Revealing mistake: When everyone first gets off the bus outside the hotel, Williams shakes hands with Margaret. If you look at his wrist you can see his real skin, not the prosthetic which is supposed to go nearly up to his elbow. It can be seen a little better in the next shot as well.