* ActorAllusion: In one scene of "Murphy Murph and the Feng Shei Bunch", Marco wears a {{Chips}} helmet.
* ExecutiveMeddling: The episode "Feast of Alvis" was supposed to be a straight-up ChristmasEpisode... until the executives rejected it. Jesus was then replaced with Alvis, [[TropesAreNotBad the worship of whom served to make Murphy look that much crazier]].
-->'''Sparks''': Your "lord"? It's a baby ''with a freaking gun, roasting over a flood light!''
* MarthDebutedInSmashBros: The original series (Sealab 2020) never aired outside the U.S., so all dubs of ''Sealab 2021'' suffer from this.
* PromotedFanboy: mcheshpants420, a member of the Creator/AdultSwim message board, who wound up writing "Fusebox" and "Dearly Beloved Seed". It's generally theorized that this is mc chris, one of the writers on the show and the voice of Hesh, simply mocking the fans.
* ThrowItIn: Aside from the HilariousOuttakes that sometimes play over the end credits, several lines throughout the series appear to be lines from the recording studio where the actor was talking to the director or otherwise cracking up. Debbie Love seems to get quite a few of these, and one particularly odd one involves Stormy, sounding unusually eloquent, arguing about whether the line should be "sticking a staple in their eye" rather than "sticking a stapler in their eye", finishing with "maybe I'm being too literal, I mean, this is a cartoon."