The given name of each kid is a reference to his/her code name. Numbuh 5 is Abigail Lincoln (the $5 bill shows Abraham Lincoln). Numbuh 4 is Wallabee Beetles (the Beatles had four members). Numbuh 3 is Kuki Sanban ("sanban" means "third number" in Japanese). Numbuh 2 is Hoagie P. Gilligan, Jr. (he is the second person in his family to have the name. Additionally in the show "Gilligan's Island" Gilligan is the first mate / second in command). Numbuh 1 is Nigel Uno ("uno" means "one" in Spanish).
Numbuh 5's evil teenage sister Cree is named after the voice-over artist who plays them both, Cree Summer.
The name of the fourth grade president, Jimmy McGarfield, is made up of the name is three former American Presidents; Jimmy Carter, William McKinley, and James A. Garfield.
The pilot episode was called Kids Next Door. The show itself was called Codename: Kids Next Door.
Each season in the series features one or more "art shows". They are experiments in various artistic styles and thus differ significantly from typical episodes. Some examples of these would be the first season's Operation: Operation T.H.E.-F.L.Y./Operation P.O.I.N.T. (2003) (an episode where no dialogue is spoken and the story is told through music), the second season's Operation: R.E.P.O.R.T./Operation: B.R.I.E.F. (2003). (each of the five main characters gives their version of the events of a mission in five different animation styles), the fourth season's Operation F.O.O.D.F.I.T.E./Operation C.L.U.E.S. (2004) (a heavy metal rock opera), and the sixth season's Operation S.C.I.E.N.C.E./Operation A.M.I.S.H. (2007) (a presentation of commercials that, in the episode's story line, characters have created to advertise their 2x4 technology).