Deliberate mistake: Though the film takes place over the course of several weeks, at night there is always a full moon.
Deliberate mistake: A branding iron loses its bright orange glow relatively fast when it's out of the fire. When the police enters the room it is still very bright orange even though it has been on the floor for some time.
Deliberate mistake: When Janine smashes the mirror she takes it directly off the wall and raises it above her head, and the reflective side would be facing behind her. The camera immediately cuts to a front view as she's throwing it down and the reflective side is in front. This was probably done for dramatic effect so that the reflective side would hit the ground first.