* CaliforniaDoubling: Much of the movie was shot in Ontario, Canada, with the University of Toronto doubling for Princeton. The White Castle in the end was actually constructed in an abandoned restaurant because there are no White Castles in Canada. Canadian chains such as Shoppers pharmacy and Lick’s Burgers can be seen.
* CareerResurrection: Creator/NeilPatrickHarris had largely pulled away from on-screen roles and had built a career in theater. However, his performance in this film electrified audiences, leading to his casting in ''Series/HowIMetYourMother'' on CBS, which then got him the hosting gig at the Tony Awards and made him ''the'' go-to song-and-dance man for a number of years.
* CompletelyDifferentTitle: In French, the title is akin to ''Harold & Kumar Hunt for the Burger''.
* DawsonCasting:
** Harold is supposed to be in his mid-20s, but Creator/JohnCho was 32 when it was released.
** Bobby Lee was in his 30s playing a young university student.
* DeletedRole: The movie originally ended with Harold meeting Maria's brother, played by Luis Guzman, who Harold initially mistakes for her boyfriend, and learns from him that Maria has gone to Amsterdam. As humorous as it was, WordOfGod decided it'd be better having Harold actually see Maria one last time before she goes to Amsterdam.
* DeletedScene: Kumar's IndulgentFantasySegue with marrying a bag of weed (while he was "breaking" Harold out of jail) was originally going to be longer and it used an entirely original song called My Sweety Weedy Pie. It was cut for time purposes.
* FakeBrit: The two British girls at Princeton were played by Canadian actresses Creator/BrookeDOrsay and Kate Kelton.
* FunnyCharacterBoringActor: Inverted with Creator/JohnCho and played straight with Creator/KalPenn, who have both said their real-life personalities are more or less the reverse of their characters'. An example would be how Penn does not smoke marijuana, is a vegetarian (the crew actually made his sliders vegetarian) and is gay (although he publicly came out 17 years later).
* PlayingAgainstType: Creator/NeilPatrickHarris, who was still best-known as the family-friendly Doogie Howser, played a debauched version of himself. He's credited as "Neil Patrick Harris as Neil Patrick Harris".
* TechnologyMarchesOn: Early on, Rosenberg and Goldstein sit down to watch the film ''[[Film/TheGift2000 The Gift]]'' on TV--solely because they've heard that Creator/KatieHolmes [[{{Fanservice}} bares her breasts]] onscreen for around 30 seconds. If the movie had been made even three or four years later, they probably would have just DVR'ed the movie and fast-forwarded to the part that they actually wanted to see (or looked the scene up on an online video streaming site). ''Nobody'' today willingly watches a movie from the beginning on live TV just to see a single scene.
* WhatCouldHaveBeen:
** According to co-writer Jon Hurwitz, had Creator/NeilPatrickHarris turned down the role, Creator/RalphMacchio was their second choice of "Wholesome 80s star".
** The producers wanted to play Music/{{Queen}}'s "We Are the Champions" as Harold and Kumar eat their White Castle burgers, but they couldn't clear the rights to do so. They settled on a remix of the "Sunrise" fanfare from "Also sprach Zarathustra".
** Instead of Hot Dog Heaven, Rosenberg and Goldstein were supposed to be at a Krispy Kreme; they refused the filmmakers permission to use their brand.

----