* ActorAllusion:
** Creator/TimCurry literally is [[Film/TheRockyHorrorPictureShow a hot dog]] who gets [[ItMakesSenseInContext covered in mustard]] in "Meat your Maker".
** While this is more of a Creator Allusion, J.G. Quintel was born in 1982, the year that Mordecai and Rigby travel back to in "Prank Callers." Plus, the title card of ''Ello Gov'nor'' (the movie, not the episode) has "©MCMLXXXII" written on it and the World Dishwashing Championship 1982 video in "Peeps".
** James Hong basically plays [[Film/BigTroubleInLittleChina Lo Pan]] during the episode "Fortune Cookie".
** Techmo is dressed up as [[Anime/CowboyBebop Spike Spiegal]] "Terror Tales of the Park III". Both characters are voiced by Creator/SteveBlum.
** EdAsner(Santa) previously portrayed Santa in ''Film/{{Elf}}''
** Terry Crews (Brock Stettman from "The Thanksgiving Special") used to be an American football player.
** Once again, Katey Sagal plays an [[AmazinglyEmbarrassingParents amazing embarrassing mom]] (cf. ''8 Simple Rules for Dating My Teenage Daughter'', ''Recess'', and ''MarriedWithChildren'', though Mordecai's mom is more like Spinelli's mom than Cate Hennessy[[note]]who isn't that embarrassing a mom[[/note]] or Peg Bundy[[note]]who is embarrassing, but doesn't really act like a mom[[/note]]).
* BadExportForYou and BannedInChina: A lot of episodes have either been edited to pieces or banned outright in Cartoon Network stations airing in the United Kingdom, Australia, the Philippines, and Latin America.
** In Poland, Romania, and Hungary, the episode "The Unicorns Have Got to Go" has been banned for reasons unknown (probably because of gross-out humor).
* CreatorCameo:
** In "Out of Commission", Cart is voiced by Toby Jones, one of the show's writers/storyboard artists (who also co-wrote the episode).
** In "Firework Run", Hector is voiced by Andress Salaff, another writer/storyboard artist of the show (who also co-wrote the episode).
** Skips' annoying cousin, Quips, is voiced by Matt Price, one of the writers of the show.
* CreatorsFavorite:
** During the San Diego Comic-Con 2014, some of the people working on the show revealed their favorite characters:
*** Matt Price, one of the writers and the voice of Quips, said Muscle Man is his favorite because he's passionate, funny, and cares about his friends.
*** Minty Lewis and Roger Craig Smith's favorite character is Eileen.
*** William Salyers' favorite character is Thomas (Death's son).
*** Sean Szeles said his favorite character was Hi-Five Ghost but changes his mind to CJ.
* TheDanza: RogerCraigSmith as Frank Smith.
* DescendedCreator:
** The creator, J.G. Quintel, voices Mordecai and High-Five Ghost after Creator/JeffBennett was replaced.
** Minty Lewis, the voice of Eileen, started out as a writer/storyboard artist on the show. When she wrote the line about the baby sea turtle eggs from "Do Me a Solid" and pitched it, they knew she was perfect for Eileen.
* {{Defictionalization}}: A company has made a real-life version of [[http://www.capitalbay.com/latest-news1/492172-could-you-handle-the-ulti-meatum-chip-shop-boss-creates-10-000-calorie-burger-within-a-burger.html the Ulti-Meatum]], citing the show as the inspiration.
* EditedForSyndication: This occasionally happens (and not just in the countries mentioned in BadExportForYou and BannedInChina above; America did do some slight editing). In "Prank Callers", when the Master Prank Caller was taking a bath, the shot of the bathroom floor had a condom wrapper on it. In all reruns, it's cropped out/digitally removed
** In "Fortune Cookie", the word "chink" (an offensive term for someone who's Chinese) was digitally removed from a dim sum cart that passed by.
** In all later airings of "The Power", "How in the H are we gonna fix this S?" is changed to "How in the heck are we gonna fix this stuff?"[[note]]though the closed captioning on TV and Netflix has the original line, and the DVD and Blu-Ray version has the actual line intact.[[/note]], and "pissed" is changed to "ticked." The same goes for "you pissed me off" in "Meat Your Maker", but, oddly, "Benson's gonna be pissed" is left intact in "Free Cake." Both instances are odd, considering that Mordecai's "Holy crap, it's real!" and "You're screaming like a fricking maniac" haven't been edited in American reruns of the episode "'Ello, Guv'nur."
** In the UK, the infamous line "How in the H are we gonna fix this S?" was changed to "How in the heck are we gonna fix this hole?" (except for Netflix UK, where the line is "Now, how in the H are we going to fix this hole?" which still [[GettingCrapPastTheRadar gets crap past the radar]] by keeping the TWordEuphemism for "hell") well before Cartoon Network America decided to edit it.
* HeyItsThatVoice:
** Creator/MarkHamill voices regular character Skips, along with the British Taxi from "Ello Guv'nor" among other one-shots, making this the ''third'' time[[note]]fifth, if you count the reruns of ''WesternAnimation/BatmanTheAnimatedSeries'' that aired on this channel after its run on FOX and the WB Network and ''WesternAnimation/BatmanTheBraveAndTheBold''[[/note]] Hamill has done voicework on a Creator/CartoonNetwork show[[note]]The first two being the original ''WesternAnimation/JusticeLeague'' series and ''WesternAnimation/TimeSquad''[[/note]] that has become notorious in most fanbases for being packed with risque content (though ''WesternAnimation/RegularShow'' was intentionally made as a sort of bridge show between AdultSwim and CartoonNetwork's more child- and family-friendly programming).
*** His voicing of the sensei from Death Sandwich sounds very reminiscent of [[WesternAnimation/{{Metalocalypse}} Mr. Salacia]].
*** The voice he uses for a young, British-accented Skips is disconcertingly close to his take on SelfDemonstrating/TheJoker or a less-effeminate take on [[TimeSquad The Larry 3000]].
** Rigby is voiced by William Salyers ([[WesternAnimation/MoralOrel Reverend Putty]] [[WesternAnimation/MaryShelleysFrankenhole Invisible Man]]).
** Creator/TimCurry is the leader of a group of cannibalistic hot dogs.
** Paul F. Tompkins is the movie store clerk in "Ello Guv'nor".
** David Ogden Stiers ([[Series/{{MASH}} Charles Emerson Winchester III]]) is Mr. Maellard.
** Creator/SteveBlum is Utopia, Muscle Bro, Techmo, and a few other one-shot characters.
** Creator/JeffBennett is a recurring VA for background characters and was the original voice of High-Five Ghost.
** Creator/RogerCraigSmith plays the new intern, Thomas, as well as Doug the Doppelganger, Low-Five Ghost, and various other voices.
** Starla, Muscle Man's girlfriend, is voiced by Courtenay Taylor ([[VideoGame/MassEffect2 Jack]]).
** Rigby's brother Don is [[Anime/{{Pokemon}} Paul]].
** Creator/AprilStewart is Susan.
** Carl Weathers ([[Film/{{Rocky}} Apollo Creed]]) is the King of Basketball in "Slam Dunk".
** Creator/RobertEnglund is "Deer Man" from "Camping Can Be Cool".
** Donald Glover, aka ChildishGambino, is Alpha-Dog in "Rap It Up".
*** [[Music/{{OFWGKTA}} Tyler the Creator]] is Blitz Comet.
** James Hong ([[Film/BigTroubleInLittleChina Lo Pan]]) is the Chinese restaurant guy in "Fortune Cookie".
** Creator/RobinAtkinDownes is Gary.
** Creator/TroyBaker is Park Avenue, the living can of spray paint, in "Under the Hood".
** [[Series/TheMightyBoosh Rich Fulcher]] is the message recorders in "Butt Dial".
** Linda Cardellini ([[Film/ScoobyDoo Velma]], [[WesternAnimation/GravityFalls Wendy]]) voices C.J. the cloud girl in "Yes Dude Yes".
** MichaelDorn is Thomas, the son of Death (no relation to Thomas, the goat intern).
** [[WesternAnimation/UglyAmericans Natasha Leggero]] is Ladonna in "Access Denied".
** FredTatasciore is Muscle Man's father, Muscle Dad and a bunch of full grown geese.
** Richard [=McGonagle=] ([[WesternAnimation/{{Ben 10}} Fourarms]], [[WesternAnimation/StarWarsCloneWars General Grievous]]) is Starla's father, Herb, and Carrie O'Key in "Karaoke Video".
** Armin Shimerman ([[Franchise/RatchetAndClank Dr. Nefarious]], [[WesternAnimation/TheGrimAdventuresOfBillyAndMandy General Skarr]], [[VideoGame/BioShock1 Andrew Ryan]], [[Series/StarTrekDeepSpaceNine Quark]], and [[Series/BuffyTheVampireSlayer Principal Snyder]]) is Buttonwillow [=McButtonwillow=] in "The Best VHS in the World".
** KurtwoodSmith is Gene the talking vending machine.
** Creator/EdwardAsner is Santa Claus in the Christmas special.
** Thomas Haden Church ([[Film/{{Spider-Man Trilogy}} Sandman]], [[WesternAnimation/TeenTitans Killer Moth]]) is Quillgin, the rogue elf.
** Creator/WayneKnight (Newman on ''Seinfeld'', Igor on ''{{Toonsylvania}}'') is the Guardian of the Friendzone.[[note]][[That70sShow Not the first time]] [[ActorAllusion he played a heavenly being that helped an awkward guy with relationship problems ...]][[/note]]
** [[http://www.youtube.com/watch?v=4_DfqThERB0 MC Lyte]] is The Demolition, "the dopest girl on the mic."
** JenniferHale is Margaret's Mom and was Mordecai's mom on the Thanksgiving Special (but not "Maxin' and Relaxin'")
** Comedian Creator/BobcatGoldthwait is Johnny Crasher from "Heart of a Stuntman".
** Creator/AliHillis is Tracy, Mordecai's date to the New Year's party, in "New Year's Kiss".
** Debra Wilson (one of the original cast members of the FOX sketch show ''Series/MADtv'' known for her impressions of Mariah Carey, Oprah Winfrey, and Whitney Houston) voices one of the members of the Intergalactic Dodgeball Council and one of the Thunder Girls in "Dodge This".
** Tim Russ ([[Series/StarTrekVoyager Lieutenant Commander Tuvok]]) voices the Sergeant and the helicopter pilot in "Portable Toilet".
** Music/GreyDeLisle voices Mona, Skips' deceased girlfriend.
** [[MarriedWithChildren Peg Bundy]] or [[{{Recess}} Spinelli's mother]] or [[{{Futurama}} Turanga Leela]] or [[SonsOfAnarchy Gemma Teller-Morrow]] (Katey Sagal) is Mordecai's mother, while Mordecai's father is Dr. Victor Ehrlich from ''StElsewhere'' (Ed Begley, Jr).
** Reggie on "New Bro on Campus" was [[TinyToonAdventures Montana Max]], [[PepperAnn Milo Kamalani]], and [[SaluteYourShorts Bobby Budnick]].
** Poland reunites the WesternAnimation/TotalDramaIsland (another TV-PG-rated CartoonNetwork show that has a following with older viewers) cast to work on this show:
*** Mordecai is Mike.
*** Rigby is Scott.
*** Skips is Chef Hatchet.
*** Pops is Justin.
*** Muscle Man is Owen and Noah.
** In Spain, Muscle Man is [[TsubasaReservoirChronicle Kurogane]], [[Manga/{{Gintama}} Gintoki Sakata]] and [[TransformersArmada Optimus Prime]].
** In Norway, Rigby is [[WesternAnimation/TotalDrama Trent]].
* KeepCirculatingTheTapes: Wanna see the uncut version of ''The Power'' (you know, the one where Rigby actually says, "Now, how in the H are we gonna fix this S")? Only place you'll get to is on the Slack Pack DVD, as for the uncut versions of ''Free Cake'' and ''Meat Your Maker'' unless you copied it the first time you're out of luck unless you find it through [[DigitalPiracyIsEvil illegal means]].
* NamesTheSame: Thomas is the name of both the park's billy-goat intern and Death's son. Rigby even says so on the episode where Mordecai and C.J. have to babysit Death's son Thomas and Mordecai calls Rigby to babysit him but he thinks he means Thomas the goat intern.
* TheOtherDarrin: Creator/JeffBennett voiced High-Five Ghost in his first two appearances instead of Quintel. The only explanation for the actor change (since both Quintel and Bennett are still alive and still doing voice work for the show) is that someone thought Jeff Bennett wasn't right for the role and decided that Quintel would be better (or Bennett missed a rehearsal, Quintel took over, and a mutual agreement was made that Quintel take over for Bennett).
** On the Thanksgiving episode, JenniferHale and Alastair Duncan voiced Mordecai's mom and dad. On the first episode that focused on them ("Maxin' and Relaxin'"), Hale and Duncan were replaced by Katey Sagal and Ed Begley, Jr.
* [[Main/RealLifeRelative Real-Life Relative]]: Janie Haddad's husband, [[Series/ComedyBangBang Paul]] [[Series/MrShow F.]] [[Podcast/ThrillingAdventureHour Tompkins]], voices a few characters, most notably a Were-Skunk in "Skunked".
* TalkingToHimself: J.G. Quintel voices both Mordecai and High-Five Ghost (after the episodes in which Creator/JeffBennett voiced him), and Sam Marin voices Benson, Pops, and Muscle Man. Both they and Creator/MarkHamill (Skips) voice several background characters as well.
** Thomas and [[spoiler: Garrett Bobby Ferguson Jr.]] are both voiced by RogerCraigSmith.
* WhatCouldHaveBeen
** For "Do Me a Solid", instead of destroying the tape, Rigby originally kept it.
** Margaret was originally not going to wear any clothes like Mordecai, but was changed for [[ThinkOfTheCensors obvious reasons.]]
** In "Mordecai and the Rigbys", there was supposed to be [[http://i.imgur.com/Yk9FZ.jpg 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", Skips was originally suppose to have a different secret. Which was [[spoiler: him being friends with the Magic Elements.]]
** The last three minutes of the Halloween special "Terror Tales in the Park" had to be redone because CN deemed it too gory and violent for kids. The end result? Rigby getting egged by a giant egg (which actually is still bad, since a later episode revealed that Rigby is deathly allergic to eggs).
** In "Trucker Hall of Fame", the flashback of Muscle Dad telling Muscle Man to take a raincoat with him on his prom was edited because the censors saw Muscle Man's line "Muscle Dad, I don't need no ''protection'' from the ''rain''!" as a blatant condom joke (or an endorsement for unprotected sex. Your call).
** Also Mordecai's mother was the mom who was critical to Mordecai. She was a Role Model of a mother to everyone else, but not in Mordecai's eyes. Also Rigby's mom is sweet, loving and protective of her son. Those are really interesting ideas, but for some reason, J.G. Quintel and the others don't want to make episodes about Mordecai and Rigby's parents, even through Benton Connor keeps recommending it to them. Although there's a Thanksgiving special that finally introduces Mordecai and Rigby's parents, they only make a brief appearances and we don't see much of their personality, and "Maxin' and Relaxin'" shows Mordecai's parents again (his mom is embarrassing, but well-meaning and his father is the sane one and a bit of a doormat).
** Much like the first Halloween special, the second one also had to have its ending changed for being too scary and violent, even for Cartoon Network, though the ending that did air ([[spoiler:where the tow truck crashes into a tree and everyone comes out as a ghost]]) didn't seem like much of an improvement in terms of eschewing death references. [[http://www.scribd.com/doc/110275736/Original-Ending-to-the-Regular-Show-Halloween-Special Here's some storyboard art showing the ending that did get rejected]].
** The "lady" the unicorns brought for Mordecai in "The Unicorns Have Got to Go" was originally supposed to be an obviously cross-dressed man in a skimpy bra, panties, fishnet, and heels outfit, but the Creator/CartoonNetwork censors asked them to replace the man with something less risque (and they did: it was a blonde biker with long hair who kind of looks like Robert Plant from Led Zeppelin)[[note]]though the animators could have also made the skimpy bra and panties into a dress, unless the censors were really against having a transvestite on the show[[/note]].
** 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, and Quintel thinks it's actually better that they did.
** According to Calvin Wong, they wanted Terry "Hulk" Hogan to voice Muscle Dad.
** In "Skips' Story" originally the Guardians of Eternal Youth were going to laugh at Walks' name choice.
** In "I Like You Hi", Toby Jones and Owen Dennis intended Yuji to be parody of reality TV personalities, specifically the faux celebrity complex, but the only reality show they both watched was ''Series/SweetGenius'' so Yuji was based off of nothing.
*** There were some jokes in the episode that had some parts removed that changed the context of the joke.
*** Yuji's tattoo was originally going to be on his forehead.
* TheWikiRule: [[http://regularshow.wikia.com/wiki/Regular_Show_Wiki Regular Show Wiki]]
* WriteWhoYouKnow: Mordecai is pretty heavily based on series creator J.G. Quintel, who even voices the character with his regular voice. Quintel even stated that Mordecai is himself as a bluejay (which is why Mordecai doesn't act like a bird).