Development Gag: Its most likely, Major plot throughout Season 7 and likely (also final season) Season 8 by starting episode "The Dome Experiment Special" seems mostly revisited and retool the original set up of show (Who so happen all Scientists [instead Zookeepers] are Human and Majority or Whole Park employee's just happens are Non-human with possibly Mitch due questioning his humanity" [in same episode that scientists and some fans in real life still thinking Mitch's appearance are seems more/less human-like], And their even quote from Main Antagonist calling them "Specimen" in Climax are soundly indeed similar to one of original set up idea that Humans are likely civilized animals/specimens)
The Other Darrin: High Five Ghost was voiced by Jeff Bennett in two episodes, but his other voiced appearances all have Quintel as his voice actor.
Mordecai's first French actor (Gerald Rinaldi) died in March 2012, so he was replaced by Emmanuel Dekoninck.
Talking to Himself: J.G. Quintel voices both Mordecai and High-Five Ghost, and Sam Marin voices Benson, Pops and Muscle Man. Both they and Mark Hamill (Skips) voice several background characters as well.
Margaret was originally not going to wear any clothes like Mordecai, but was changed for obvious reasons.
Quintel originally intended for the set-up of the show to be about Mordecai and Rigby working at a zoo full of humans and was very set on it. The higher-ups decided against it for possible reason that if they add background African-american or Native American characters in Zoo rooms and you know rest, and Quintel thinks it's actually better that they did. Put however.
In "Mordecai and the Rigbys", there was supposed to be a scene where Mordecai and Rigby ask Benson why there were instruments in the garage. Benson has a flashback when he used to be a hippie where his ex-girlfriend, Veronica, who is also a gumball machine, leaves him for a business man.
In "Skips Strikes", Skip was originally suppose to have a different secret. Which was him being friends with the Magic Elements.