Revealing mistake: When the mother gets into an accident after her tire blows, the ghost shows up. It is floating above her car. Notice the seam where the ghost is on the car. When the scene shakes slightly, the ghost shakes too indicating it was a poorly superimposed shot.
Revealing mistake: In one shot when Alice is in the shower, as she turns for the soap you can tell she is wearing brown underwear. (00:03:30)