Ella's (Fivel Stewart) shirts are always changing. Sometimes she's wearing a completely different shirt/outfit in one scene from the previous. Sometimes the shirt's aren't even on worn the correct way as seen when she's wearing her white top with the dog picture. Another time is when she's talking to Dr. Keegan and suddenly she has to leave but runs into the principle, her shirt goes from her white top to her brown sweater top from earlier scenes.
In the movie they reuse the same background characters. Including using the same actor in a shot reverse shot in the background.
Booboo Stewart's character, Jonah, in the beginning you can see his under that he got from the Ellen DeGeneres show.
While Kristen is wandering around at night, she goes outside. When she turns to leave, the crew is reflected in the cabinets on the far side of the room.