To get into character, Bill Murray spent time with Hunter S. Thompson by drinking, shooting and generally having a great time at Thompson's Colorado ranch. After filming ended, Murray continued to act "Gonzo" through the beginning of the next season of Saturday Night Live (1975), to the annoyance and consternation of cast and crew members.
In an early scene, the establishing shot outside a seedy bar includes two characters lighting cigarettes. They are musician Neil Young and music producer David Briggs, who contributed to the soundtrack selection and recording.
Ralph Steadman, who did illustrations for Hunter S. Thompson's books, drew the title cards for this movie. The closing titles credit Steadman for "Title Splatters", "Gonzo Calligraphy" and "Incidental Artwork".
Hunter S. Thompson was eventually brought aboard the film's production as "executive consultant", but claimed he had no substantial role other than to have "wandered around and fired machine guns on the set".
During the opening credits, Peter Boyle receives first billing and Bill Murray receives second billing. DVD and video covers, movie posters, and promotional materials tend to give Murray top billing.