- Casting Gag: Melvyn Douglas plays McKay's father. Douglas was married to former Congresswoman Helen Gahagan Douglas, who was defeated by Richard Nixon in his 1950 Senate race.
- Life Imitates Art: This film originated the practice of politicians wearing an American flag pin on their lapel, when H.R. Haldeman saw the movie and suggested it to Richard Nixon. Ironically (or not), it's the film's villain, Crocker Jarmon, who sports the pin rather than McKay.
- Write What You Know:
- The film's screenwriter, Jeremy Larner, was the primary speechwriter for Eugene McCarthy during his 1968 presidential campaign. Larner won the Academy Award for Best Original Screenplay.
- Bill getting punched in the nose at a campaign stop and getting accosted by someone while he's using a urinal were both actual incidents that happened to McCarthy. Also the scene where McKay and his entourage try to join a group of African-Americans playing basketball, only to accidentally terrify them, happened to Larner and several other McCarthy aides during a campaign stop in Milwaukee.
Trivia / The Candidate