Trivia: Harold & Kumar Go to White Castle
- Dawson Casting: Harold is supposed to be in his mid-20s, but John Cho was 32 when it was released.
- Deleted Role: 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, Word of God decided it'd be better having Harold actually see Maria one last time before she goes to Amsterdam.
- Funny Character, Boring Actor: Inverted with John Cho and played straight with Kal Penn, who have both said their real-life personalities are more or less the reverse of their characters'.
- Playing Against Type: Neil Patrick Harris. He's credited as "Neil Patrick Harris as Neil Patrick Harris".
- What Could Have Been: According to co-writer Jon Hurwitz, had Neil Patrick Harris turned down the role, Ralph Macchio was their second choice of "Wholesome 80s star".
- The producers wanted to play 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.
- Word of God: Some speculate that the British twins are a nod to the Pigeon sisters in The Odd Couple.