Towards the end of the movie, when "The Woman" is attacking all the people who escaped from underneath the stairs, she has a knife in her hand. At one point, she attempts to stab one of the people, but misses and instead, jams the knife into the door. Well, the door is noticeably fake because we don't see a knife mark exactly where the knife hit. There is a slit in the door about inches away and it appears about 2 seconds after she jammed the knife into the door.