Continuity mistake: When Jack is leaving the shed with the bug bomb, the canister switches from being under one arm to the other.
Visible crew/equipment: In the lead-in to the movie, as it is showing the aerial shots from the helicopter, at one point you can actually see the shadow of the helicopter in the bottom right hand corner.
Plot hole: Interesting to note...in the opening scene where Pete is talking to Jack, Pete says that the boiler pressure needs to be dumped every night or it'll blow because the safety valve has been rusted shut for the last twenty years. Then he continues on to say that last year's caretaker, Grady, killed himself, and he was alone at the hotel. So...why didn't the boiler explode last winter? (00:02:20 - 00:05:55)