* HeyItsThatGuy:
** In the original Los Angeles-based episodes of ''Mathnet'', the chief, Thad Green, was played by Creator/JamesEarlJones. Despite a change in chiefs with the move to New York City, Jones made one appearance via phone in a season 4 episode.
** The ''Mathnet'' segments in particular featured a number of notable cameos from people in the world of music, television and theater. [[WesternAnimation/TheSimpsons Yeardley]] [[Series/HermansHead Smith]], Music/WeirdAlYankovic, Marcia Wallace, and [[Series/{{Bewitched}} Dick Sargent]] and [[Series/{{MASH}} McLean Stevenson]] (as rivals in the same episode), just to name a few, all appeared.
** This also applied to people working off camera. First- and second-season writer David Yazbek later co-wrote the theme songs to ''Series/WhereInTheWorldIsCarmenSandiego'' and ''Series/WhereInTimeIsCarmenSandiego'' and also wrote songs for ''Series/BearInTheBigBlueHouse''. Pat Tuesday and George Frankly even appeared in a first-season episode of ''Where in the World..'', in which they gave out clues to the gumshoes to where the crook had gone.
** One of the regulars in the non-''Mathnet'' sketches, Reg E. Cathey, later turned up on ''Series/HouseOfCardsUS'' as restaurateur Freddy Hayes.
* HeyItsThatVoice:
** Gary Owens, alias the title character in ''WesternAnimation/RogerRamjet'', as Lt. Dirk Niblick of the Math Brigade. (Furthermore, like ''Roger Ramjet'', the Dirk Niblick segments were written by Jim Thurman and animated by Fred Crippen.)
** Jim Thurman as Glitch in the ''Mathman'' segments and as supporting characters in the Dirk Niblick segments.
* KeepCirculatingTheTapes: The series has not been rerun since the early 2000s, when it was rerun on Creator/{{Noggin}}, and there are currently no DVD releases planned. Domestic recordings do exist of many episodes, and they sometimes show up on Website/YouTube, but they are nowhere near exhaustive, and quality varies widely.
* TooSoon: An exception - not long after the September 11 attacks, Noggin aired an unedited episode in which George Frankly casually discussed having dinner at Windows on the World at the World Trade Center.
* WrittenInInfirmity: The likely reason Kate Monday is holed up in the "Mathnet" episode "The View from the Rear Terrace".
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