* CreatorCameo: Jeff Kinney plays Holly Hills' father. And the director of the last two movies appears in a newscast in the third.
* DawsonCasting: Lots of high schoolers playing preteens in the movie. To the point the third movie was rushed in production so the actors could be used one last time, before they officially got too old to pass as early teens.
* HeyItsThatGuy:
** [[Film/KickAss Hit Girl]] (or [[Film/LetMeIn Abby]] or [[Film/FiveHundredDaysOfSummer Rachel]] ...or Film/{{Carrie|2013}}) runs the school newspaper in the first film.
** And how nice of [[Series/StargateSG1 Dr. Fraiser]] to drop by for dinner in the second film.
** Greg has [[Film/SurvivalOfTheDead Boy]] as his JerkAss older brother in all three films.
*** Horror fans may also recognise Rodrick as [[Film/SawVI Brent]] or [[Film/SurvivalOfTheDead Boy]] as well.
*** He also portrayed [[VideoGame/AssassinsCreedII Ezio Auditore]] in the live-action short film ''Assassin's Creed: Lineage''.
** Well, hi there [[Series/HowIMetYourMother Ted's cousin and Grant]][[note]]Zachary Gordon has been in two episodes of HIMYM-- ''How Lily Stole Christmas'' and ''The Stinsons''.[[/note]]
** Greg previously played [[NationalTreasure a kid who gave Nicholas Cage a hard time at the White House Easter Egg Roll.]]
** Greg has [[Series/{{Jessie}} Emma & Ravi]] as his {{love interest|s}} and FunnyForeigner [[TheRival rival]], respectively.
* NamesTheSame: Dr. Salazar Kagan, Greg's dentist, while {{depraved|Dentist}}, was [[Franchise/HarryPotter not responsible for founding Hogwarts or opening the Chamber of Secrets.]]
* TechnologyMarchesOn: In the webcomic, Manny breaks Greg's Walkman by stuffing a cookie in the cassette slot. The novel changed it to a video game system.
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