Michael Cimino wrote the script on spec with Clint Eastwood already in mind for the lead role.

Eastwood liked the script so much that he initially intended to direct it himself, but after meeting Cimino he decided to hand him the directing job instead, giving Cimino his big break and feature-film directorial debut.

Cimino said that if it had not been for Eastwood, he never would have had a career in film.

Cimino patterned Thunderbolt after one of his favorite 1950s films, Captain Lightfoot.

Eastwood became available for the project after turning down the lead role in Charley Varrick just as that production was nearly ready to begin.

The film was shot in 47 days between July and September 1973 across several Montana towns including Ulm, Hobson, Fort Benton, Augusta and Choteau.

The fictional 'Warsaw Exit 250' freeway sign was actually the real Interstate 15 exit for the unincorporated community of Dearborn.

Eastwood disliked doing more than three takes per shot; assistant director Charles Okun recalled that Eastwood was the only one who could veto Cimino's request for extra takes, often saying 'No, we got enough.'

Cimino later credited the fast shooting pace he developed on this film for helping him when Heaven's Gate ran into trouble and United Artists demanded a much shorter cut delivered quickly or he would be fired.

Clint Eastwood vowed never to work with distributor United Artists again, feeling the film's promotion had been poorly handled despite its box-office success.

Jeff Bridges received an Academy Award nomination for Best Supporting Actor for his role, and Eastwood himself reportedly believed his own performance was Oscar-worthy.

The film's success, along with Cimino's TV commercial work, led producer Michael Deeley to approach Cimino to direct and co-write the Oscar-winning The Deer Hunter (1978).

In November 2025, a remake was announced at Amazon MGM Studios with Ryan Reynolds attached to star and produce, and film editor Shane Reid set to make his directorial debut.