Continuity mistake: The foot pedals on the grand piano are missing in the scene where Wakko takes a mop to clean Beethoven's mouth out.
Continuity mistake: When the Warners first step into Beethoven's house, the doorknob plate vanishes.
Continuity mistake: When Dot is about to sing for Beethoven on top of the piano, her microphone switches hands between shots.
Answer: According to the Animaniacs Wikia: "Baloney is one of the few people capable of truly terrifying Yakko, Wakko and Dot, largely due to being impervious to their violently physical brand of humour and his inability to understand how much they despise him."
lionhead