In the episode The Flag and Further Snags the interior set for Nora's is very odd,when Wally has the front door open there are houses opposite,yet at that time I think it was a working mill opposite,also the room where Nora is standing on the table has a wall behind her which is almost level with the front door, yet as the camera moves about it shows a flight of stairs going up behind that wall,which is really clever as they would then be outside the front of the building