The closing credits end with the written statement, "Portions of The Missouri Breaks were filmed at the Bovey Restorations, Nevada City, Montana."
       The 11 Aug 1975 Newsweek reported that producer Elliott Kastner commissioned novelist Thomas McGuane to write the original screenplay for The Missouri Breaks, and then used the project to recruit director Arthur Penn, and actors Marlon Brando and Jack Nicholson, who were admirers of each others’ work. According to an article in the Dec 1975 Vogue, the screenplay was based on McGuane’s historical study of “rustling,” or livestock theft, during the settling of Northern Montana.
       An article in the Jan 1976 Millimeter mentioned that the character “Lee Clayton” was based on nineteenth-century gunman Tom Horn. The 24 Aug 1975 LAT reported that Brando’s desire to modify the character, adding an Irish brogue and assorted bizarre behaviors, resulted in two days of retakes. According to Vogue, Brando accepted the role because he needed money to finance his film on the plight of Native Americans, and for sea farming projects on his South Pacific island. Brando requested that Nicholson’s role be changed to that of a Native American, and when the request was denied, the actor threatened to “walk through his part.” After disallowing any candid photography on the set, Brando stopped production for several hours because a photographer friend, Stephani Kong, was prohibited from using her camera. He also called the production team “barracudas” for delaying the making of a documentary on The Missouri Breaks. Brando reportedly read his lines from cue cards, and had them placed among a row of cabbages during one of his scenes with Nicholson. Even so, the actor altered his lines during each take. For another scene, Brando wanted to paste cue cards on the face of actor John McLiam. When McLiam complained of not being able to see, Brando offered to cut holes for his eyes. Ultimately, the cards were attached to the wall behind McLiam.
       Principal photography began early Jul 1975, and included two weeks in Virginia City, MT, followed by another nine weeks on Rosell Ranch, fifteen miles outside of Billings, MT. According to Millimeter, Brando’s final scene in the film was photographed inside a U. S. Post Office in Billings. A news item in the 17 Sep 1975 Var announced that photography had been completed, and that post-production would begin in New York City.
       According to the 7 Dec 1975 Parade, Kastner purchased McGuane’s screenplay for $400,000, Penn was paid roughly $600,000 and a two percent interest, and Kastner paid himself $600,000, plus a percentage of the profits. Actress Kathleen Lloyd was paid $20,000, while the 9 Aug 1976 LAT reported that Brando received a salary of $1 million and ten percent of "all gross receipts in excess of $10 million," for five weeks of shooting. Nicholson was on set for ten weeks, and was paid $1.25 million and ten percent of all "gross receipts in excess of $12.5 million." On 14 May 1976, Nicholson sold back five percent of his royalties to Kastner for $1 million, to be paid within ten days of the agreement. When Kastner failed to pay within the allotted time, Nicholson filed suit in the Los Angeles Superior Court on 8 Jun 1976.
       The Missouri Breaks was actress Kathleen Lloyd’s first feature film. According to the 31 May 1976 LAT, casting director Gene Lasko saw her portray a deaf woman in a television series and invited her to read for “Jane Braxton.” She worked with Lasko, Penn, McGuane and producer Robert M. Sherman for eight days before she was accepted for the part. In the article, Lloyd disputed the LAT statement by film critic Charles Champlin that described “Jane” as being “as contemporary and out of place in Wild West Montana as a steel-belted radial.” After reading a book about the women who settled Montana, Lloyd determined that “there is no reason why such a woman couldn’t have existed in 1883.”
       The 11 May 1976 Var quoted McGuane, saying that Brando and Nicholson were “willful and capricious,” and that he distanced himself from The Missouri Breaks when Brando and Nicholson began to reconceptualize the film. However, Penn described the actors as “brilliant,” noting that both he and McGuane were grateful to Brando for enhancing the picture with his improvisational touches, particularly the scene in which Brando wakens a sleeping Randy Quaid by dropping a live grasshopper into his mouth. Penn also credited Elliott Kastner for getting the film made after the screenplay “floated around Hollywood” for two years. In an interview in the 21-28 May 2003 Time Out London, Penn recalled that the screenplay was unfinished, which created the opportunity for improvisation. He said that McGuane was re-editing his first directorial effort at that time, 92 in the Shade (1975, see entry). According to the 11 Aug 1975 Newsweek, McGuane and Penn collaborated on rewrites during the first two weeks of shooting, and added three confrontations between Brando’s and Nicholson’s characters to the screenplay.
       Vogue reported that the film’s crew, ensconced at the War Bonnet Inn near Billings, was threatened with eviction. Crewmembers had brought family, friends and pets to stay with them for the summer, and incurred the disapproval of the management. Montana’s assistant governor intervened, and half of the crewmembers were allowed to stay. Those who were evicted encountered some difficulty finding new lodgings.
       The death of a horse during filming was reported in the Oct 1975 National Humane Review. A horse named “Jug” struck its hoof against a submerged automobile body while swimming across the Yellowstone River, and died of a heart attack soon after. According to Harold Melniker of the Hollywood, CA, chapter of the American Humane Association (AHA), the accident would have been avoided if the river bottom had been checked. AHA offered to send a representative to the location at no cost, but the producers declined. A Montana AHA representative was also denied access, although the producers explained that the set was closed to everyone, without exception. Melniker issued a protest to Motion Picture Association of America President Jack Valenti. The Missouri Breaks was given an “unacceptable” rating in the May 1976 National Humane Review, not only for the death of the horse, but also for the slaughter of rabbit, which is shown in detail onscreen. The 22 Jun 1976 DV reported that the American Society for the Prevention of Cruelty to Animals (ASPCA) urged a boycott of the film.
       The 21 Apr 1976 Var announced that United Artists Corp. would be distributing 900 prints for the opening of The Missouri Breaks, the largest opening in the history of the company to date. The 21 May 1976 DV estimated United Artists’ investment in the film to be $10 million, and anticipated gross receipts of $10 million in the first week. The 9 Jun 1976 Var reported that the film grossed $9 million in its first two weeks.
       The Missouri Breaks opened to lukewarm reviews; several critics, including those from the 19 May 1976 Var, the 24 May 1976 Time and the 7 Jun 1976 New West, were unsure whether the film was to be taken seriously. The 20 May 1976 NYT review described the scene in which the rabbit is killed as “more brutal and more shocking” than the final confrontation between the two principals. Both the 21 May 1976 LAT and the 21 May 1976 LAHExam singled out Lloyd as a promising newcomer. In the Time Out London article, Arthur Penn stated that, “reviewers were expecting a great shoot-em-up. It failed their expectations.”
       The 27 Apr 1976 DV reported that an album based on the soundtrack for The Missouri Breaks, recorded by composer John Williams, and a single of the theme song, recorded by Ferrante and Teicher, would be released by United Artists Records on 19 May 1976 to coincide with the nationwide opening of the film.