After they change their nun's habits with the nurses and their uniforms, they make a comment as to whether the seams of their stockings are straight yet when the police sergeant strips the nurses of the nun's habits, the nurse is wearing her stockings and suspenders.
Sister Mary asks them why they are wearing the formal nuns costume as they don't wear them at this convent - they wear the casual look but the nun reading the book in the entrance is wearing the formal outfit.
When Brian's and Charlie's car runs out of gas, we hear the engine stall and the starter engine being cranked, while we still see Brian holding the steering wheel with both hands.