Trivia

The line "Look out, Haskell, it's real!" was actually dubbed in after the shooting. It was supposedly what Haskell Wexler was thinking to himself and he wanted to include it.

In the psychedelic nightclub sequence, the band seen performing on the stage is The Litter, a Minneapolis-based group. However, everything that is heard, starting when "America is Wonderful" is flashed on screen, is by Frank Zappa and The Mothers of Invention. Three tracks edited together are heard: excerpts of "The Return of the Son of Monster Magnet" and "Are You Hung Up?" followed by most of "Who Needs The Peace Corps?"

The main character was originally called "John Cassavetes" and was in fact going to be played by actor-director John Cassavetes. When he withdrew from the film due to a scheduling conflict, the character's name was changed to "John Cassellis" and Robert Forster was cast in the role.

Film was originally released with an "X" rating in 1969, but was re-rated "R" in 1970 under new guidelines.

Some of the background intercom chatter playing during the first scenes shown of the television station that John Cassellis works at is the same intercom chatter used in George Lucas' student film Electronic Labyrinth THX 1138 4EB (1967). Paul Golding, who served as an editorial consultant for this film, had also been a collaborator on some of Lucas' other student films.