Visible crew/equipment: In the first shot of the theatre play, you can see the boom mike quickly entering the picture to the left on the screen. (00:01:40)
Factual error: During the theatre play you can see they are using electric stage lights. Nice move for a series plotted almost 300 years ago. (00:01:55)
Revealing mistake: The bomb that is thrown at the Prince explodes before the lit fuse actually burns down far enough. (00:03:15)
Factual error: At Ms. Miggins' when she says, "There's ever so much hard work," you can see her wearing a bra under her corset. Bras didn't exist at that time. (00:06:35)
Answer: According to the IMDB.com's quote page for Blackadder The Third, it's "Aahhhhh. Hot potato, orchestra stalls, Puck will make amends. Owwwwww."
Gary O'Reilly