Continuity mistake: After Crocker discovers that Gregory is in his house, she tries to hand him the key to the basement at the Hotel. In one shot, when facing Crocker, the handle of the key is facing him, but when the camera is facing Gregory, the key's handle is is facing her.
Revealing mistake: At the very beginning of the film, we see the transfer vehicle carrying Jack driving down the road. You can tell in several shots that the (fake) snow isn't really falling, but is just being blown in front of the camera from off-screen, especially since there's no snow hitting the road, and it's coming from the side, not above.