Other mistake: Pretty much everyone in the film, especially Alice, seems to be able to fire their weapons without reloading at all.
Other mistake: When Lawrence is looking at his wound in the mirror, it has slightly healed. Later, when Sir John visits Lawrence in the asylum, he shows the bite mark he got from the feral child to Lawrence. Since Sir John is also a werewolf, the bite mark should not be there.
Other mistake: In the scene where Judy and Becca are strapped to beds in the high school and the principal is coming with a pitch fork, at first there is a close up of the fork (when the principal is dragging it) and its dry with no blood, the principal walks over to his first victim and right before he raises the fork it is shown covered in blood so much that some has ran on to the floor.
Other mistake: We are seeing the movie as if we were watching recordings, that's why we see the surveillance camera shots as the device installed to change from one camera to another would let us. It takes very short time from one camera to another,but in some cases, as to follow things to happen, the shot stays in one angle (camera) for a longer period, not keeping the timing for the mentioned device.
Other mistake: Bobby extracts 2 teeth forcibly to get into the final room, however when he's in the other room his mouth is no longer bleeding. The blood wouldn't stop that quickly. (01:02:15 - 01:10:00)
Other mistake: Kim is putting Sally back in her own bed at night to sleep however the window shows daylight. (00:47:56)
Other mistake: In the last scene when Jeep, Charlie, and the baby are driving off, the gearshift of the truck is located in "park". That is located at the topmost point of the gearshift's travel.
Other mistake: Blake jumped through the window, shattering the glass and propelling many fragments through the air and towards/onto Edgar and Zoe, but no-one got cut. (00:34:10)