In "Stump Looks For His Roots":
The cook shows Norb and Dag a school out the window that was built by Stump. You hear a buzzing noise in this scene and Dag cries out "There's a giant fly attacking the school!" The cook quickly smashes the fly with a piece of chewed gum. Problem is we never actually SEE the fly on the window. That buzzing noise comes from NOWHERE!
Norb: I'm Baron Once-Bad-Now-Goodbeaver!
Scientist: Congratulations, Baron, uh... Once-Beaver-thingy. You saved the world!
The music being played as the camera goes up on a cliff to show Muscular Beaver is from the 1989 film, "Batman".