These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Big Lipped Alligator Moment: Occasionally, such as Gecko briefly gaining the ability to speak and smoke a pipe in "The Amazing Colossal Duckman".
Crosses the Line Twice: Too many instances to count. As with Family Guy (a show that might be considered its spiritual successor), curious viewers watching their first episode of Duckman should keep two tallies - one for the number of times you laugh, and one for the number of times you feel insulted and/or begin to vomit. If the first tally is larger than the second, you're a fan.
Dude, Not Funny!: Most of the Fluffy and Uranus abuse was pretty funny, but the one from "All About Elliott" was just disgusting. Duckman eats Fluffy and Uranus and a couple days later, we see Fluffy and Uranus back in the office, shivering in terror and looking disheveled. Duckman actually digested and crapped them out. Yuck.
"Funny Aneurysm" Moment: Lampshaded in "Bev Takes a Holiday". Charles and Mambo ask Bernice how she plans to have enough energy to be a mom and a Congresswoman. Bernice replies that she'll take power naps in the bathroom like Strom Thurmond. Immediately, a disclaimer appears on the screen, stating to disregard the joke if Strom Thurmond has died around the time of the episode's premiere (or rerun).
Doubly funny as this episode was rerun on Comedy Central the day after Strom Thurman died. Possibly done so deliberately.
Before he died, Jim Varney voiced Walt Evergreen, president of a tobacco company. In case you're curious, Varney died of lung cancer.
Jerkass Woobie: Duckman's behavior and antisocial attitude stems from the fact he still misses his wife, and that she was the only person who could keep him in line.
The ending song to "America, The Beautiful" can be this or Narm Charm, depending on the viewer.
They Just Didn't Care: In some scenes of episodes during the fourth season, Charles and Mambo's heads somehow switch places. Usually, Charles's head is on the left while Mambo's is on the right. But then, you'll occasionally hear Dana Hill's (or Pat Musick's) voice coming out of the right head. How did they screw that up when they never had trouble keeping this straight in the first three seasons?
To see if the audience was paying attention?
In "Days of Whining and Neurosis", Grandma-ma clearly wheels herself around in one brief scene. I thought she was comatose?
In "Westward, No!" Duckman visits a relative's catfish ranch in Louisiana, which is depicted as an arid, rocky desert. It would be a simple Rule of Funny gag, except no one ever even lampshades how utterly wrong that is. It seems like the writers really thought there are deserts in Louisiana.