Corrected entry: The episode "Bells" and the episode "Head" appear to be inversed in their order - Lord Percy has a beard at the beginning of "Bells," and shaves it off. However, in "Head," he's got it back. In all of the other episodes, he has no beard. Also, the song at the end of "Head" mentions Lord Blackadder's origins (it mentions Edmund's great-grandfather), which makes it more a follow-on from the 1st series.
Corrected entry: Blackadder's house is confusing, particularly the "front" room we spend the series in. In "Potato", Blackadder fires an arrow down on the crowd, and calls down, showing that that room is on the second floor. In "Beer", this room leads into the corridor (which is level with the room), and the front door is level with the street, as shown by the Puritans entering.