The film's sequences at "Harvard" were actually shot at UCLA.
In creating the sound for the mystical pot plant (Ivory), sound designer Andrew Somers (uncredited) used a Theremin and a set of Obsidian Chimes. For the sound of the giant bong, (and the sound of Ivory appearing) they recorded inhaling through an actual bong.
The film is named after the hit 1995 hip hop song How High by the starring duo Method Man and Redman.
Dean Cain is a reference to Dean Cain the actor who played superman in the series. This is a subliminal message of getting high like superman
Tracy Morgan cameos as the baseballer in ghost form a la field of dreams.