Continuity mistake: When they are first hearing the pounding on the doors, Luke Wilson opens the door to see what is outside, as he is opening the door, the pounding from the other hotel room startles him. He yells and looks at the other door, and when the shot continues, the door to his room is now closed.
Continuity mistake: When Luke Wilson grabs the first video off the top of the TV that one has the label pulled off, But the piece that was left was whole. But when it cuts to him putting it in the VCR the piece that was left was two pieces, Then when he takes the first video out and puts in the second one it is the one with the two pieces of label on it.
Continuity mistake: When the couple crawl through the underground passageway and come up to the hotel office, we see a shot behind Luke Wilson looking through, and the flashlight is in his right hand. Cut back to the shot facing him, and you can see his left hand and several fingers from his right hand sticking up - impossible if he was holding the flashlight a moment before.
Factual error: The apple from which Amy was cutting a slice in the car in the beginning of the movie is later discovered "planted" by the bathroom sink after the first blackout. At least 2 or 3 hours have passed between when Amy cut the apple and when she finds it by the sink in the room, but the apple hasn't browned at all during this time, when it reality it would have browned within minutes of being cut.