In "House of Crime", a clue states that the guy who's kidnapping everyone has a grudge.
Donald: What!? I don't hold a grudge? (everyone looks at him suspiciously) What?
(scene transition; Donald is locked in the elevator)
Donald I WANT A LAWYER!!!
The Running Gag of Donald following an annoyed Goofy shouting "Everybody loves me! I never get mad!".
Another running gag involves Donald getting trampled by a gaggle of Disney characters in several episodes.
In "Donald Wants to Fly", Donald dons a pair of donkey ears because donkeys can't fly. Cue the flying donkey from The Three Caballeros.
King Larry messing around with Horace's controls in "King Larry Swings In".
The crew reminding Donald what happened the last time royalty visited the club.
In "Unplugged Club", Minnie asks Mickey if he wants a time-out in his wheel. Cue the largest hamster wheel you ever saw.
In "The Stolen Cartoons", Minnie suggests Mickey take a drink, followed by Mickey drinking out of a giant pet cage water bottle.
In "Gone Goofy", Mickey asks Donald if he's going to give Goofy a (literal) pink-slip to get him fired, Donald hesitates for a moment before shouting yes.
In "Clarabelle's Big Secret," Chernabog's cameo where he reveals he's afraid of the dark.
In the pilot episode when Donald takes over the House, he keeps trying to rename the place to "House of Duck", only to instead given plaques reading "House of Muck" and "House of Yuck", ending with... "House of Pancakes".
Donald sleeping on the job while momeraths hop right over him in "House of Genius"
In another Goofy's Extreme Sports segment, on paracycling, Goofy engages in some aerial acrobatics as he falls. As he does this...
Narrator: As the ground looms, it is time to activate the parachute. (Goofy gets into a reclining position while falling.) Narrator:I said,ACTIVATE THE PARACHUTE!!! (Goofy does so — underneath him.) Narrator: And you should always open it above you. (The parachute gets tangled all over Goofy's body, wrapping him up like a mummy.)