When Andrea is setting up the camera, she moves a picture to the right to reveal a camera, in which she sets to record. As she leaves the room in the next scene, without her moving it, the picture is conveniently placed in-front of the camera to conceal it while Mark goes to play music.
When Mark is stripping his pants are shown on and off between shots.
In the beginning of the movie Andrea is talking to her makeup artist and says that she has never had bangs before (but thinks they look good), but in the flash back scene where she finds her boyfriend cheating on her she has bangs in the shots before she has the scarf on her head.