A running gag in "Red Wind" is pretty amusing: Geraldo Rivera's character calling Mitch "Mr. Ripple Pecs". Besides the line itself, part of what makes it funny is that it's Geraldo saying it.
In "Someone to Baywatch Over You", there's a scene where Matt is pushed off his boat by a St. Bernard. It's not meant to be funny conceptually, but the abrupt way it's staged and edited make it ridiculous. Plus, just the fact that a St. Bernard did it is silly. That's right: Beethoven is a murderer.
Due to Actor Allusion, one can't help but laugh when Mitch asks the baby he's babysitting in "Sweet Dreams" if he wants to watch Knight Rider.