The title comes from a nursery rhyme by British writer Oliver Goldsmith (1730?-1774).

In the scene where Doctor Spivey is interviewing McMurphy, this whole scene is improvised. Spivey (Dr. Dean Brooks) is the ACTUAL doctor of the institute in real life, and was simply told to interview Jack Nicholson (McMurphy) as if he was a real patient. Nicholson had to improvise and get from the beginning of the scene to the end.

In order to produce the film, Michael Douglas decided to quit "The Streets of San Francisco" in 1975. The decision would eventually earn Douglas the Academy Award for Best Picture.

If you look closely at the people standing on the quay when the Hyak returns to the harbor, one of the by-standers is Jack Nicholson's long-time partner, Angelica Huston.

Ken Kesey never saw the movie. He was furious over changes the producers made to his novel, particularly reducing the Chief (the book's narrator) to a minor role. He also wanted Gene Hackman to play McMurphy.

In mental-health circles, "Cuckoo's Nest" is known simply as "The Movie."

Writer Ken Kesey wrote "Cuckoo's Nest" while under the influence of LSD.

Ken Kesey, the author of the novel upon which the film was based, was originally hired to work on the screenplay but was fired soon thereafter.

The music at the begining and end of the film is in fact someone playing the musical saw.

Kirk Douglas played McMurphy in the stage version of the novel. His son Michael would later produce the movie.

The film helped trigger the de-institutionalization movement in mental health care (i.e. "mainstreaming" patients into society through community-based, outpatient treatment, rather than imprisoning them in state mental hospitals) beginning in the 1970's.