* CreatorBacklash / OldShame: LaurenFaust has made it abundantly clear that she is not at all proud for writing "Everyone Knows It's Bendy."
* CrossDressingVoices: Terrence is voiced by Creator/TaraStrong.
** Cheese is voiced by Creator/CandiMilo, who also voices Madame Foster and Coco. And [[WesternAnimation/ChalkZone that other blue dude.]]
** In the Japanese-language dub of the show, Mac is voiced by Makoto Tsumura, who voiced Anime/AstroBoy in the 2003 adaptation. [[Anime/DigimonTamers She also voiced an adorable young boy who created his best friend.]]
* DawsonCasting: Eight-year-old Mac is voiced Sean Marquette, who was about fifteen or sixteen when the show began. He was not replaced after he had gone through puberty. Instead, he had his voice digitally pitched up. It is obvious if one compares episodes from Season 1 to episodes afterward.
* FakeBrit: Kansas native Tom Kane as Mr Herriman, who has a British accent even if he probably isn't actually British. He mostly pulls it off, but certain pronunciations may give the game away.
* HeyItsThatVoice: Where do we start?
** Bloo is the second version of [[Disney/{{Bambi}} Friend Owl]], [[KingdomHeartsChainOfMemories the ruler of Castle Oblivion]], [[VideoGame/FirstEncounterAssaultRecon Lieutenant Steve Chen]], and [[VideoGame/FinalFantasyXII Captain Basch]].
*** In Japan, his voice actor is Creator/NoriakiSugiyama ([[{{Anime/Naruto}} Sasuke]])
** Eduardo is SpongebobSquarepants, [[RockosModernLife Heffer]], and [[Disney/WinnieThePooh Rabbit]], as of the 2011 movie.
** Coco, Madame Foster, and Cheese are [[MuchaLucha The Flea]], [[WesternAnimation/MyLifeAsATeenageRobot Nora Wakeman]], and [[ChalkZone Snap]], respectively.
** Frankie and Goo are [[WesternAnimation/TheFairlyOddparents Vicky]], [[WowWowWubbzy Wubbzy]], [[WesternAnimation/TheGrimAdventuresOfBillyAndMandy Mandy]], [[WesternAnimation/AvatarTheLastAirbender Azula]], and [[WesternAnimation/DannyPhantom Sam]].
*** In Sweden, Frankie is also Azula.
** Wilt is [[WesternAnimation/{{Futurama}} Hermes Conrad]], [[WesternAnimation/JusticeLeague Green Lantern]] and [[SamuraiJack Samurai Jack]].
** Mr. Herriman is [[ThePowerpuffGirls Professor Utonium]] and [[StarWarsTheCloneWars Yoda]].
** [[PlayingAgainstType Believe it or not]], Terrence is {{Tara Strong}}.
** Mac is [[VideoGame/KingdomHeartsII Pence]].
** Ivan and Uncle Pockets, two one-off imaginary friends, are [[Disney/LiloAndStitch Pleakley and Gantu]], respectively.
* InspirationForTheWork: The inspiration for the show [[https://twitter.com/CrackMcCraigen/status/610248929213464576 came from]] when Craig [=McCracken=] and Lauren Faust adopted three dogs from an animal shelter, and wondered what their lives were like before.
* KeepCirculatingTheTapes: Seasons 1 and 2 have been released on DVD, though both have been out of print for years (with sets of season 2 going for as much as $70.00! ). Luckily the entire series is available on iTunes and the Playstation Network, as well as Creator/{{Hulu}} Plus.
** As of November 2014, the third season is now available on DVD- as a Warner Bros. burn-on-demand exclusive.
* OutOfOrder: The episodes on the first season DVD set are listed differently than how CN aired them, as they go from production order. This makes sense as "Busted" feels like it takes place after "House of Bloo's".
* TalkingToHimself: Among the main and secondary cast, Creator/GreyDeLisle plays Frankie, Goo, and Duchess while Creator/CandiMilo is Coco, Madam Foster, and Cheese. The voice actors for the main cast besides Mac's also tend to provide most of the voices for {{One Shot Character}}s and the show's many {{Recurring Extra}}s.
* {{Tuckerization}}: Jackie Khones's name is a {{Spoonerism}} of Executive Producer Khaki Jones.
* WhatCouldHaveBeen: In the earliest sketches of the show, Mac was blond and had shorter hair.
** [[http://cmcc.deviantart.com/art/Eduardo-Development-76338423 See]] [[http://cmcc.deviantart.com/art/Coco-Development-76338828 some]] [[http://cmcc.deviantart.com/art/Frankie-Deveopment-76339145 concept art]] [[http://cmcc.deviantart.com/art/Bloo-Development-76337898 from]] [[http://cmcc.deviantart.com/art/Wilt-Development-76338091 Craig [=McCracken=]'s]] [[http://cmcc.deviantart.com/art/Mac-Development-76337605 Deviantart here.]]
* WordOfGod: Years after the show ended, the show's creator provided numerous odd bits of information on Twitter:
** [[https://twitter.com/CrackMcCraigen/status/611928065912868867 Only children could make imaginary friends]], then this ability [[GrowingUpSucks is lost]] [[InvertedTrope upon completing]] [[PubertySuperpower puberty]]. Terrence was able to make one because he wasn't fully post-pubescent then.
** [[https://twitter.com/CrackMcCraigen/status/612061383434219520 Both of Frankie's parents are alive.]] Having to grow up with Mr. Herriman around [[https://twitter.com/CrackMcCraigen/status/609812747715350528 soured Frankie's dad on the idea of imaginary friends]], so he [[https://twitter.com/CrackMcCraigen/status/609813042860142592 never let Frankie have one]]. The only one she ever made [[https://twitter.com/CrackMcCraigen/status/609817339400355840 she had to give up]], and one of the reasons she works at Foster's [[https://twitter.com/CrackMcCraigen/status/609817724760408064 is so she might see that friend again some day]].
** The CityWithNoName the show it set in is located [[https://twitter.com/CrackMcCraigen/status/609737072014790657 somewhere in the Pacific Northwest]].
* WriteWhoYouKnow: Mac is based on creator Craig [=McCracken=] as a child. Frankie, meanwhile, is based on his wife, Creator/LaurenFaust, as she is now. The concept came to him when the two of them adopted a puppy and Craig made up a story about what his life was like before they got him.