The Burgermeister falling down the stairs because of a toy duck. The choppiness of the animation is the best part of the gag: each of his limbs goes limp one after the other with a significant delay, all the while he has this slack-jawed, bug-eyed look of agony on his face.
The This Reminds Me Of A Song that Jessica sings which is completely irrelevant to the plot, but is still funny because of the 1960's acid colors.
The Running Gag with people criticizing Kris' clothes. When it's brought up a second time, he responds with this: