While making this film, Sam Peckinpah's alcoholism was so advanced that he would have to start the day with a large tumbler of vodka to stop shaking. He would be drinking grenadine by mid-afternoon. After that, he was too drunk to work. James Coburn recalled that Peckinpah was only coherent for four hours a day.
Al Pacino told a German interviewer in 2014 that he was offered the role of Billy the Kid, but it didn't work out because he couldn't ride a horse. He was also wary of Sam Peckinpah's hard-living reputation.
Although Kris Kristofferson was widely felt to be too old to play Billy the Kid, it should be noted that James Coburn was much older than Pat Garrett.
Kris Kristofferson and Sam Peckinpah had several heated arguments while making the film, and others on the set often thought they would fight physically. Peckinpah, always very confrontational, wanted to fight Kristofferson, but said he feared Kristofferson, a former Army Airborne Ranger, would "kill him". Kristofferson answered, "Yeah, Sam, I think you're right". In spite of this, Peckinpah referred to Kristofferson as a "fucking great guy" and said that working with him was "one of the greatest experiences of my life".
Due to a bent flange, all of the shots made with one Panavasion camera were out of focus on the right side, making the footage unusable. MGM had refused Sam Peckinpah's request to have a camera mechanic on-call in Durango, and because all the footage was sent back to Los Angeles for processing, the problem wasn't discovered for several weeks. MGM finally sent a camera mechanic to the set after the faulty lens was replaced. By then, the film was several days over schedule and several hundred thousand dollars over budget.