* AccidentallyCorrectWriting: Accurately predicted the actual ending for ''Anime/FullmetalAlchemist: Brotherhood'' long before it aired.
* ActorAllusion: Moosk from "Operation: K.N.O.T." is a parody of Minsc from the ''Franchise/BaldursGate'' franchise, right down to being voiced by Creator/JimCummings.
** Also, Creator/FrankWelker voices Professor XXX-L, who in the "Kenny and the Chimp" short, dealt with all kinds of crazy chemicals and diseases; furthermore, he's always got a different set of animal body parts, making him a sort of mutant. All of which seems a bit similar to Welker's character in ''WesternAnimation/SwatKats'', [[EvilutionaryBiologist Dr. Viper]], who got mutated into a half-animal creature after dealing with an unstable chemical, and spoke with a similar voice (albeit with hissing as opposed to XXX-L's lisp, and it's a bit more sinister).
* ContestWinnerCameo: In "Operation: P.R.E.S.I.D.E.N.T.", complete with no spoken lines, and an overly detailed face.
* CrossDressingVoices: Averted; even though most of the boys are about 10 to 12, the voice actors are all adults who play their respective genders (Numbuhs 1, 2, and 4 are played by men and Numbuhs 3 and 5 are played by women).
** There are, however, a few boys voiced by women: Numbuh 84 voiced by Creator/JaniceKawaye, Numbuh 363 voiced by Creator/JenniferHale, the Numbuh 44 twins voiced by Creator/LaurenTom, Numbuh 88 voiced by Creator/CreeSummer, and Willard voiced by Creator/TaraStrong.
** In the Japanese dub, Numbuh 5 is voiced by ''a man''.
** Numbuh 2 was going to have this; see WhatCouldHaveBeen below.
** Creator/CreeSummer as Cree Lincoln, a rare non-live-action-sitcom use.
** Also somewhat worth mentioning is Creator/RachaelMacFarlane, who plays Numbuh 362 a.k.a. Rachel.
** Creator/DeeBradleyBaker as Bradley the Skunk.
** In the failed pilot "Kenny and the Chimp", Creator/TomKenny plays Kenny.
* DawsonCasting: Played straight. None of the actors voicing the kids are actual children (but most have voiced kids on other shows: Creator/LaurenTom played Connie on ''WesternAnimation/KingOfTheHill'' and Cree Summer is best known as Elmyra Duff and rarely-seen character, Mary Melody[[note]]a black girl who looks like a younger, more politically-correct version of So White from the banned WesternAnimation/LooneyTunes short "WesternAnimation/CoalBlackAndDeSebbenDwarfs"[[/note]] on ''WesternAnimation/TinyToonAdventures'', Penny on ''WesternAnimation/InspectorGadget'', and identical twins Tessa and Vanessa on ''WesternAnimation/PepperAnn'')
* DuelingShows: When Kids Next Door was chosen as the winning show to be made into a series in 2001, another show was also chosen as well called ''A Kitty Bobo Show'' but was never picked up or aired beyond a pilot episode.
* ExecutiveMeddling: A positive example: The 2x4 technology came about when Creator/CartoonNetwork wanted the high-tech gadgets changed since [[ItsBeenDone it was already done on]] ''WesternAnimation/DextersLaboratory''. Creator Tom Warburton later stated that it became his favorite thing about the show.
** Numbuh One: voiced by Ben Diskin, who also voices Numbuh Two.
** Also, a Fake Aussie -- Numbuh Four, voiced by Creator/DeeBradleyBaker.
** [[FakeIrish Fake Scottish/Irish]] -- Numbuh 86, voiced by Jennifer Hale.
* FanNickname: Ashley, the sole unnamed girl of the Delightful Children.
* InkSuitActor: Billy from "Operation: C.L.O.S.E.T.", one of the one-time-characters Creator/TomKenny voiced, looks like him as a child.
* KeepCirculatingTheTapes: It's been released on DVD a few times, a couple of random "Best of" DVD's, but never in box-sets or a complete season. The entire series is available on iTunes and the Playstation Network though, and the first 3 seasons have been put on Netflix.
* LoadsAndLoadsOfRoles: Once you start noticing the nuances, Creator/CreeSummer, Creator/DeeBradleyBaker, Creator/TomKenny, and Creator/JenniferHale are ''everywhere''.
* NamesTheSame: No, this Father not the BigBad from ''Manga/FullmetalAlchemist'', although their roles in their respective series are surprisingly similar.
* RealLifeRelative: The boy who gets abducted by the Abominable Snowsuit in "Operation: C.L.O.S.E.T." and his mother are voiced by Creator/TomKenny and his wife, Jill Talley.
* RealitySubtext: The first video for the G:KND "teaser" was apparently leaked; typing in "Morbidcrab" (the Youtube account that leaked it) on the Rainbow Monkey site gives the message "why you gotta did that?". In the second video released after the countdown [[spoiler:Numbuh Vine yells at Numbuhs Three and Four for posting the video early.]]
** Happens more than often for Numbuh Four, as Creator/DeeBradleyBaker voices dozens of other extra roles, including villains (notably the Toilenator), operatives, and background characters.
** Numbuh One and Numbuh Two. Both are voiced by Ben Diskin.
** Cree Summer voices both Abigail and her sister [[TheDanza Cree]].
** The Delightful Children from Down the Lane's voice actors are three of the Sector V voice actors.
* TheyWastedAPerfectlyGoodCharacter: WordOfGod says that they "never got around to telling Numbuh 60's story".
** Numbuh Three was originally going to speak only in Japanese (with subtitles), while Numbuh Five was originally going to be TheVoiceless. The reason both those ideas were scrapped was because it would have resulted in both girls having no lines and possible protests over alleged sexism (and possible racism, since both girls aren't white [Abby is African-American and Kuki is Japanese-American]).
** "Operation: S.P.A.N.K.E.N.S.T.E.I.N." was originally a thirty-minute Thanksgiving special, "Operation: S.P.A.N.K.S.G.I.V.I.N.G.".
** Also, Lizzie's original character design was changed before her debut episode was made. Apparently her old appearance was too ugly for the execs.
** One episode, "Operation: T.R.E.E.S.", an episode-long ShoutOut to Creator/DrSeuss and specifically to ''The Lorax'', was axed early in its production, due to it running right on the heels of the movie version of ''WesternAnimation/HortonHearsAWho''.
** The [[JokeCharacter Toiletnator]] was originally going to be a one-time character whose only appearance would have been in "Operation N.O.-P.O.W.U.H."
** Grandfather was originally going to have a wife.
** [[http://networkedblogs.com/LavA8 According to this one blog post by Tom Warburton,]] some of the villains (Mr. Wink and Mr. Fibb, Mrs. Goodwall, Professor XXXL) having animal parts was "part of a larger story arc that fell by the wayside."
** Creator/BenDiskin wasn't always going to voice Numbuhs 1 and 2. Numbuh 1 was going to be Creator/TomKenny, then an actual twelve-year-old (until he hit puberty), ''then'' Ben Diskin was chosen. Meanwhile, Numbuh 2 was going to be voiced by Sue Rose (the creator of ''WesternAnimation/AngelaAnaconda'' and ''WesternAnimation/PepperAnn'').
** Originally, Numbuh 4 ''was'' TheChosenOne destined to defeat Dodgeball Wizard, until one of the writers suggested [[spoiler:that it should instead be his little brother, Joey]].
** The teasers for GKND was going to lead to a SequelSeries before Creator/CartoonNetwork rejected it in favour of ''WesternAnimation/ThePowerpuffGirls2016'' and ''WesternAnimation/Ben102016''. Though Samurai Jack getting a revival certainly means hope isn't lost.
* TheWikiRule: [[http://knd.wikia.com/wiki/Main_Page The KND Code Module.]]