Deliberate mistake: It is shown throughout the film that card keys are to be used to open the hotel room doors; this is a security measure that is used for doors in elegant and expensive hotels (if not all). There are no hotels that use this measure without having break-safe metal material inside of these doors, yet the killer and cops are shown breaking down doors fairly easily. Add to this the fact that only thin slices of wood are shown breaking off of the doors, not metal nor even the card-keying device.
Deliberate mistake: When the Dragon Emperor is giving his Terracotta army the speech near the end, you see a shot that pans across the faces of several of his soldiers. A few shots later, this exact same shot is played in reverse. It is very easy to tell if you look at the way the camera moves up and down to catch the different faces.
Deliberate mistake: Several times, you see an exterior shot of Nathan's house, and it is very clear that it is the same shot being used over and over, sometimes reversed.
Deliberate mistake: When Ami's school friend is killed, a short sword is stabbed into the top of her head. Less than a half-second later, we see her face is totally coated in blood, and she gurgles even more blood before dying. There simply has not been enough time for such a volume of blood to have dripped down her face.