Audio problem: When Bob carries Charlotte back to her room, he opens her door using a regular key (you hear the "teeth" going into the lock, as as it turns). But when he comes out of the room and closes the door, you can see it's actually a card-key access room (the card-lock is on the right side of the door). While some card keys (with holes) rely on mechnical force and makes sounds like a regular key, it is an older system. This is a top Tokyo hotel, which would only offer the best and most modern equipment to its customers, i.e. top-of-the-line, silent (non-disturbing) card keys.