Throughout the episode Dot's jacket was black. But near the end of the episode when Beethoven confronts the Warners before he says "Why you... you...!", Dot's jacket was pink.
Why would the sound of the Warners' chewing distract Beethoven? It's already been established in the episode that Beethoven has already gone nearly deaf.
Beethoven: (pulling Dot away) That is all I can take!
(Wakko goes over to Beethoven and pulls out a dipstick that reads "All I Can Take")Wakko: You're about a quart low... (puts the dipstick back in Beethoven's mouth)
Beethoven: Do you know who I am?
Yakko: No, but hum a few bars and we'll figure it out.
Beethoven: I am Ludwig von Beethoven, world famous composer and pianist.
Yakko: You're a what?
Beethoven: A pianist.
Yakko: (to audience) Goodnight, everybody!
Yakko: (to Beethoven, about his hearing device) You really shouldn't go putting stuff like that in your ear--you'll go deaf.
Beethoven: I AM DEAF!
Yakko/Wakko/Dot: Too late!