Trivia

Universal agreed to do Winchester '73, for which Stewart would receive top billing and, most important, half the film's gross profits after Universal recouped its investment. Stewart did not receive a salary. The film made him a millionaire.
--Source: The Last Mogul: Lew Wasserman, MCA, and the Hidden History of Hollywood, Page 154

Fritz Lang was originally slated to direct this movie. When he backed out, James Stewart recommended Anthony Mann. In the early 1930s Stewart had worked with Mann in the theater.
--Source: Anthony Mann, Page 79

At the time of filming, James Stewart was anxious to appear in more challenging roles, as he was worried that the general perception was of him as a limited actor. “I had to toughen up. And I found that in Westerns, I could do it and still retain what I was”. He found director Anthony Mann very helpful in breaking that perception.
--Source: Anthony Mann, Page 79

There was a shooting competition in Deadwood (USA) on 4 July 1876 which was reputedly won by black cowboy Nat Love. This notion was transferred to Dodge City so that Wyatt Earp, Virgil, and Bat Masterson could be worked into the story Winchester '73.

On the laserdisc and DVD, James Stewart gives audio commentary about the making of the movie. It was the only such commentary he ever did.

There were only 133 One-of-a-Thousand Model 1873's made.

James Stewart spent a lot of time practicing with the rifle so he would look like an authentic westerner.

At the time of release there was some ridiculing from the press at the idea of James Stewart, the "thin man", playing a tough westerner. (Broken Arrow (1950) had not been released, even though it had been filmed first). Members of the audience were heard to gasp in shock at the scene where Stewart angrily confronts Dan Duryea.

Will Geer initially felt he was badly miscast as Wyatt Earp.

Lux Radio Theater broadcast a 60 minute radio adaptation of the movie on November 12, 1951 with James Stewart reprising his film role.