Crispin Glover infamously appeared on Late Night with David Letterman (1982) in 1987 dressed, and in character, as Rubin Farr. This caused much confusion to David Letterman as he, after almost being kicked in the face by Glover, walked off his own set while still on the air.
When Crispin Glover did his infamous David Letterman appearance in character as Rubin, it wasn't to promote the film. Trent Harris was still writing the screenplay, and the movie wouldn't come out until four years later. However, the appearance did wind up connecting onto the movie as being "the movie about the character who tried kicking David Letterman four years earlier."
When Rubin and Ed enter the abandoned trailer, they find graffiti that says "Andy Warhol sucks a big one."
Crispin Glover portrayed Warhol in Oliver Stone's film The Doors (1991).
Actor Peter Boyle originally had the role of Ed Tuttle, and began filming on September 24, 1990. However, two weeks after filming began, Boyle suffered a stroke and had to leave the film altogether. Howard Hesseman stepped in to replace Boyle, and shooting resumed on October 16, 1990.