Revealing mistake: When Baldrick is on the metal spit rotating by the fire, the fire is just a light up board.
Revealing mistake: When Queen Elizabeth arrives in disguise, Blackadder welcomes her and is about to open the door to the closet, but you can see the door is being pushed up from the inside, probably by a crew member. (00:16:50)
Revealing mistake: When Percy is holding the 'Green' in his hands, light of the green reflects on the wall behind Blackadder. However the way Percy is holding the 'green' in front of Blackadder, Blackadder's shadow should be on the wall behind him, but it isn't. It's obvious green lighting is used to light up the back wall. (00:18:20)
Revealing mistake: When the Baron punches Baldrick into the cell wall, it wobbles. (00:17:20)
Revealing mistake: After Blackadder accidentally kills Smedly with one of the suicide pills, he starts ranting about how useless Smedly is as a hero, because he was dumb enough to fall for the old 'poisoned cup routine.' As he does so, you can see the supposedly dead Smedly behind him, still breathing normally.
Revealing mistake: When Blackadder lifts the huge turnip it looks really light. A turnip that size would weight a fair bit.
Revealing mistake: At the very end of the episode, right after Edmund drinks the wine, the camera switches to a close-up. Watch the very animated 'dead' extra right behind Edmund who seems to be unsure whether the scene is in the bag yet or not. (00:29:25)
The Witchsmeller Pursuivant - S1-E5
Revealing mistake: The edges of Blackadder's bald cap are visible next to his right ear when he is visited by the queen and princess. (00:24:45)
Revealing mistake: When Flash says "I've got a plan and it's as hot as my pants", his moustache is seen falling off.
Revealing mistake: It is apparent that the door Flash pushes Percy through is fake. The door bends inwards like polystyrene when it should be made out of wood.
Revealing mistake: The bomb that is thrown at the Prince explodes before the lit fuse actually burns down far enough. (00:03:15)
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