There is a scene where Natalie's room mate is chatting with someone on-line. You find out later that it is the killer. She goes to the bathroom before they are to meet to freshen up. The scene goes from her to something else and back to her. In one scene she is wearing black lipstick, then a few seconds later they go to something else, then right back to her and she isn't wearing it. It may be the other way around, but clearly, in a time-frame of seconds, she has lipstick on and then doesn't and then does again.