When the group first finds Nicole's body she has duct tape over her mouth (just as she does in the video). The camera angle changes to the group then back to Nicole and the tape is gone.
When Michael and Amber are in the basement and Amber starts crouching towards him, Michael says "I see now". In this shot, Amber's hair is already seen on his shoulder, although she has not reached him yet.
When Jennifer shoots Amber, the blood on Jennifer's face disappears and then reappears.