* ActorAllusion: At one point, Alan Eppes appears to have been involved in [[WellIntentionedExtremist an act of civil disobedience gone horribly wrong]] as a younger man. [[spoiler:He wasn't]], but actor Judd Hirsch played a similar role in Sidney Lumet's ''Running On Empty''.
** At the end of "Blackout", Alan turns on the television, saying late night is when they play "the classics", and the theme for ''Series/{{Taxi}}'' starts up.
** When it is discovered that Larry's been living in the Steam Tunnels, Mildred mentions playing ''Dungeons and Dragons'' there. Peter [=MacNicol=] portrayed the male lead of the ''Film/{{Dragonslayer}}'' movie.
* CastTheExpert: Bill Nye as a scientist.
* HeyItsThatGuy: David Krumholtz has been seen as Mr. Universe in ''[[Series/{{Firefly}} Serenity]]'', and Wednesday Addams' geeky boyfriend in ''[[Series/TheAddamsFamily Addams Family Values]]''. He also played Michael in ''Film/TenThingsIHateAboutYou'', and Goldstein in ''Film/HaroldAndKumarGoToWhiteCastle''.
** Which ''also'' features [=MacNicol=] as the [[TastesLikeDiabetes overly-cheery camp counselor]].
** Krumholtz is also Bernard in ''TheSantaClause''.
** [[AllyMcBeal John Cage]] is Dr. Fleinhart.
*** Fleinhart was also Yavosh in ''[[Film/{{Ghostbusters}} Ghostbusters 2]]''.
** [[Film/IndependenceDay The Fly's dad]] is the father, and [[NorthernExposure Dr. Joel]] the big brother of the Eppes family.
** The Native American from ''YoungGuns'' is the ColdSniper.
** Judd Hirsch is best known for playing Alex Rieger on ''{{Taxi}}''.
*** He also played the father and adult version of David Krumholtz's character in the play ''Conversations With My Father'', Krumholtz's big break.
** Charlie's frienemy is that dude from ''Orange County'', aka Creator/TomHanks' son.
** Krumholtz also played guest star D.W. Moffet's brother on ''Chicago Sons''.
** [[Series/BuffyTheVampireSlayer Spi]][[Creator/JamesMarsters ke]] (complete with accent) holds a woman hostage in an elevator in "Guilt Trip."
* HeyItsThatPlace: Most of the outside scenes at [=CalSci=] was filmed at the Caltech campus (fitting, since [=CalSci=] is clearly a fictionalized version of Caltech).