Continuity mistake: When Anna is talking to her friends at school, her shirt has a patch of white fabric with the guitar design on it. When she is arguing with her mum about her door, the white patch of fabric is gone. It changes back and forth several times.
Continuity mistake: When Pei Pei calls for her mother, she comes from the kitchen. She sees Anna and Tess and tries to escape by going back through the door she came from, but when the camera cuts back to her, she is about to enter the other door. (00:49:48)
Answer: Drummer: "what are you doing?" Anna/Tess: "I don't know, it's not working." Drummer: "Just do it".