Louise Fletcher was so upset with the fact that the other actors could laugh and be happy while she had to be so cold and heartless that near the end of production she removed her dress and stood in only her panties to prove to the actors she was not "a cold-hearted monster".
During filming, a crew member running cables left a second story window open at the Oregon State Mental Hospital and an actual patient climbed through the bars and fell to the ground, injuring himself. The next day The Statesman Journal in Salem, Oregon reported the incident with the headline on the front page "One flew OUT of the cuckoo's nest".
Author Ken Kesey was so bitter about the way the filmmakers were "butchering" his story that he vowed never to watch the completed film and even sued the movie's producers because it wasn't shown from Chief Bromden's perspective (as the novel is). Years later, he claimed to be lying in bed flipping through TV channels when he settled onto a late-night movie that looked sort of interesting, only to realize after a few minutes that it was this film. He then changed channels.
Will Sampson, who plays Chief Bromden, was a park ranger in Oregon in a park near where the movie was filmed. He was selected for the part because he was the only Native American the Casting Department could find who matched the character's incredible size.
The script called for McMurphy to leap on a guard and kiss him when first arriving at the hospital. During filming, director Milos Forman decided that the guard's reaction wasn't strong enough and told Jack Nicholson to jump on the other guard instead. This surprised the actor playing the second guard greatly, and in some versions he can be seen punching Nicholson.
Most of Jack Nicholson's scene with Dean R. Brooks upon arriving at the hospital was improvised - including his slamming a stapler, asking about a fishing photo, and discussing his rape conviction; Brooks's reactions were authentic.
Director Milos Forman relied heavily on reaction shots to pull more characters into scenes. In some group therapy scenes, there were ten minutes of Jack Nicholson's reactions filmed even if he had very little dialogue. The shot of Louise Fletcher looking icily at Nicholson after he returns from shock therapy was actually her irritated reaction to a piece of direction from Forman.
When Louise Fletcher neared the end of her Best Actress Oscar acceptance speech, she finished with a unique touch (a first in American Sign Language): "For my mother and my father, I want to say thank you for teaching me to have a dream. You are seeing my dream come true. Thank you."
Dean R. Brooks was a psychiatrist and director of the Oregon state hospital where the film was made. During filming, Brooks correctly diagnosed William Redfield with the leukemia that would kill him 18 months later.
Mel Lambert, who played the harbor master, was a local businessman rather than an actor; he had a strong relationship with Native Americans throughout the area, and it was he who suggested Will Sampson for the role of Chief Bromden.
Louise Fletcher was signed a week before filming began, after auditioning repeatedly over six months; director Milos Forman had told her each time that she just wasn't approaching the part correctly, but kept calling her back.
Rumors that production shut down because Jack Nicholson had hair plugs implanted are false (this can be verified by actually looking at his scalp). The story, as related by production designer Paul Sylbert, was that Nicholson and director Milos Forman had very different ideas about how the narrative should play out; for example, Forman thought that the ward should be in bedlam when McMurphy showed up and Nicholson posited that his character would have absolutely no effect on the mental patients if they were already riled up, which would have negated the purpose of his character and therefore much of the plot. Nicholson and Forman both refused to give an inch, each believing he was right and the other was wrong. The "two months" that Nicholson was supposed to have disappeared was actually closer to two weeks, and he didn't "disappear". In actuality, Nicholson spearheaded a coup among the other actors and refused to let Forman run rehearsals, running them himself instead. During production, Nicholson and Forman spoke to each other through the cinematographer, but faked a friendly relationship when the media and studio personnel would show up to the set. This is one explanation why Nicholson doesn't appear on any of the DVD special features.
The cast and crew had to become accustomed to working with extras and supporting crew members who were inmates at the Oregon State Mental Hospital; each member of the professional cast and crew inevitably worked closely with at least two or three mental patients.
In the novel, Nurse Ratched's first name is never revealed. In the film, when the hospital committee meets to discuss McMurphy's behavior, Dr. Spivey calls her "Mildred". Also, when McMurphy returns from ECT and sits down at the group therapy session, he calls her "Mildred".
This was the second film to win the grand slam of the Oscars: Best Picture, Best Director (Milos Forman), Best Adapted Screenplay, Best Actor and Best Actress. The first was It Happened One Night (1934), four decades earlier.
During the ECT scene, McMurphy says "A little dab will do ya" as the nurse is putting conductor gel on the side of his head. This phrase, not in the original script, is a reference to the advertising jingle of Brylcreem hair cream, which was a popular hair care product for men in the 1960s and 1970s.
Milos Forman said he directed the movie in a naturalistic style significantly contrasting with the "totally stupid socialist rallies and movies" which were common in his native Czechoslovakia. "I was fascinated just to see real faces on the screen," he said. "That's what cinema verite [like Titicut Follies (1967)] taught me."
Toward the end of the film, when Harding and Martini are playing cards, both use the word "hovno", Harding echoing Martini. "Hovno" is a word in Czech, director Milos Forman's mother tongue, meaning "shit."
The play opened on Broadway in New York City, New York, USA on 13 November 1963 and closed on 25 January 1964 after 82 performances. The opening night cast included Kirk Douglas as R.P. McMurphy, William Daniels as Dale Harding and Gene Wilder as Billy Bibbit.
Kirk Douglas starred in the 1963 Broadway production after buying the film rights prior to publication; he later passed the film rights to his son Michael Douglas, but kept a percentage of the profits. Every major studio had declined to make the film during the period he was trying to star in it. Kirk had met Milos Forman in Prague while on a State Department tour and promised to send him the book after deciding he would be a good director for the film; the book never arrived, probably confiscated by censors of the Czech government, which was Communist at the time. Ken Kesey wrote a screenplay for the production, but Forman rejected it because Kesey insisted on keeping Chief Bromden's first-person narration.
A portion of the original NBC Radio broadcast of Game 2 of the 1963 World Series was used for the scene where the orderlies are listening to the game on the radio. Hall of Fame baseball announcer Ernie Harwell can be heard on the broadcast.
Accepting the Best Picture award, producer Michael Douglas said that "Cuckoo's Nest" was the first picture since It Happened One Night (1934) to receive the four major Oscars: Best Picture, Best Director, Best Actor, and Best Actress. However, Douglas incorrectly stated the Capra classic's year of release as 1937, not 1934.
Neither the film nor Ken Kesey's 1962 novel made specific reference to Oregon State Hospital. Kesey was inspired by his experiences working at a veterans' hospital in California, and set his novel at an unnamed institution in Oregon.
Haskell Wexler worked 31 days on the film as cinematographer. His replacement Bill Butler worked 30 days and then had to leave to work on another project. That left the door open for William A. Fraker to come on board and work uncredited on the boat sequence.
The magazines seen on the shelf (in the scene where McMurphy is announcing the baseball game) include National Geographic dated August 1960 and February 1961 as well as a copy of Life Magazine dated March 29, 1963.
To call Ken Kesey's time at the VA hospital in Palo Alto is misleading. While a graduate student in Creative Writing at Stanford, he volunteered for experiments on the effects of LSD - which gave rise to the many surreal parts of the novel (deleted, along with the narrator's role, by Milos Forman). Kesey's experience with LSD led to the legendary bus trips, the Trips Festival, and all the events chronicled in Tom Wolfe's 'The Electric Kool-Aid Acid Test'.
A patient hired by the production company had a stutter that he had had all of his life. He was so inspired by his responsibilities while working for the producers that his stutter permanently resolved.
According to Michael Douglas, before production began, he, Saul Zaentz, Milos Forman and Jack Nicholson were travelling to Salem, Oregon via Portland to meet Dean R. Brooks to determine if he could play the role of the Doctor. Around that time they had received a tip about a forest fire ranger from Yakima, Washington, Will Sampson, who could possibly play Chief, a role they had been trying to fill for a while. While waiting in the Portland airport, Sampson's flight from Yakima was arriving and as the passengers started exiting, they saw Sampson in his cowboy hat and boots, and Nicholson knew instantly that he had to play Chief. They were all so excited about finding Chief and instead of having a quick meeting in the airport so Sampson could back to Yakima, they all got in the small plane that Douglas and company were using, and went straight to Salem with Sampson. Unfortunately their plane didn't have enough seats to accommodate the extra passenger so Jack Nicholson had to sit on Sampson's lap.
When McMurphy first meets the Chief (approx. 6:16), the Chief must be standing on a lifting box. You can't see his feet in the shot. Jack Nicholson is 5 foot 10. Will Sampson is/was 6' 5". In the shot, Nicholson's shoulders appear only to come up to Sampson's elbows. Also, the finished height of most doorways is 6' 8" and Sampson's head appears to extend higher than that in the shot. Even accounting for perspective, he might be on a 5"+ box. Nowhere else in the movie is the height difference so apparent.
Ken Kesey was so upset by the finished film that he sued Douglas and Zaentz for allegedly breaking a verbal agreement to not make wholesale changes from the novel. "They took out the morality ... they took out the Combine - the conspiracy that is America." He sued for 5% of the film's gross along with $800,000 for damages (equivalent to about $3.5 million in 2015). He eventually settled for 2.5% of the gross.
20th Century Fox was at one point interested in distributing the film, and agreed to finance the entire production if they rewrote the ending to allow McMurphy to live. Producer Saul Zaentz took the film somewhere else.