The hinges on Jerry's door have problems. The first time, the hinges are on the left side of the door (as one exits) - but the hinges are on the outside of the door, meaning it could only open outwardly - except it opens inwardly. Then, when Tuffy exits the big door with the armor helmet on, there are no hinges visible. Then, after writing on the blackboard, the door opens inwardly as if the hinges had switched to the right (but no hinges are visible). Then, as Tuffy returns with Lilli's first response, the hinges are back on the left side (but on the outside) - and the door opens inwardly. Finally, as Tuffy exits to deliver the letter to Marie, the door opens as if the hinges are on the inside (they are not visible from the outside, so it is assumed).