In the episode 'Beer', Edmund goes to visit lord Melchet who is 'sick' with a hangover. After the exchange, Edmund walks out of the room which is supposedly in an Elizabethan castle. On the way out, however, he accidentally knocks the wall which, if you watch carefully, moves, vibrates if you will, with the blow, because it is only made of plywood and so forth. It's really small and almost unnoticeable, but it does kind of blow the illusion a bit, huh?