* HeyItsThatGuy: The police officer that pulls the Griswolds after dragging the dog is Deputy Halik from ''MovingViolations''.
** Cousin Eddie's daughter is a very young Jenna from ''Series/ThirtyRock''.
** [[AmericanPie Mr. Levenstein]] sells Clark the Family Truckster.
** ''European Vacation'' is filled with this for European audiences, as the supporting cast was drawn from comic and character actors from each country featured. Just to name a few: British comic actors Mel Smith (the London hotelier), Robbie Coltrane, Maureen Lipman (other guests in the hotel), Ballard Berkeley (the second motorist), and Creator/EricIdle (the injury-prone cyclist), French character performers Didier Pain (the camera thief) and Victor Lanoux (one of Ellen's kidnappers), and German comedy veterans Willy Millowitsch and Erika Wackernagel (the Griswolds' unwitting German hosts).
*** Meanwhile, for American audiences, ''Pig in a Poke'' is presented by [[Series/TheAddamsFamily John Astin]] and announced by [[Series/RowanAndMartinsLaughIn Gary Owens]].
** After ''Christmas Vacation'', Rusty will move to California and become a [[Series/TheBigBangTheory physicist]], and Audrey will become [[NaturalBornKillers a serial killer.]]
*** In addition, the parade host is played by [[Series/ThePeoplesCourt Doug Llewelyn]].
** The Kamp Komfort clerk is [[TheMarvelousMisadventuresOfFlapjack Captain K'nuckles]].
* [[TheOtherDarrin The Other Rusty & Audrey]]: While Chevy Chase and Beverly D'Angelo kept reprising their roles as the Griswold parents for the first four films, their kids were played by different actors each time: Anthony Michael Hall, Jason Lively, Johnny Galecki and Ethan Embry played Rusty while Dana Barron, Dana Hill, Juliette Lewis and Marisol Nichols played Audrey.
* ThrowItIn: In ''European Vacation'', as they're checking into a hotel, Clark accidentally refers to both Rusty and Audrey as his "daughters". This was a mistake on Chevy Chase's part, but was left in because it was so Clark Griswald-ish. If you watch closely, Chase has an OhCrap expression afterward, but then shrugs it off [[TheShowMustGoOn and continues the scene.]]