Revealing mistake: Right after Sage plays chicken with the cops, the cop car is shown peeling out in reverse to follow her down the alley. The dust from the burnout is ejected towards the back of the car. Being a Crown Vic, the car has rear wheel drive but the dust should be moving opposite the car's direction. What this shows is that the car was actually being pulled backwards as it attempted to accelerate forwards. What's more is that even the sound is of a car spinning its tires opposite to being dragged. (00:12:50)
Revealing mistake: When the American man throws a square concrete tile at the monster it reacts (moves its foot in pain) before the tile actually makes contact. (00:16:11)