The studio hated Gregory Peck's authentic period mustache. In fact, the head of production at Fox, Spyros P. Skouras, was out of town when production began. By the time he got back, so much of the film had been shot that it was too late to order Peck to shave it off and reshoot. After the film did not do well at the box office, Skouras ran into Peck and reportedly said, "That mustache cost us millions."
The large painting on the wall behind Gregory Peck's chair in the barroom is "Custer's Last Fight", painted in 1884 by Cassily Adams and reproduced as a lithographic print by Otto Becker from Adams' original painting. These prints were distributed in 1896 to bars and taverns all over America by the Anheuser Busch Co.
Based on the life and exploits of an actual western gunslinger named John Ringo, a distant cousin of the outlaw Younger family. The real Ringo was a ruthless murderer and survivor of the vengeance ride engaged in by Wyatt Earp and "Doc" Holliday after the ambushes of Wyatt's brothers, Morgan and Virgil, following the Gunfight at the O.K. Corral. Also unlike the movie's account, the actual John Ringo--his real name--suffered a severe bout of melancholy following a visit to his family in California in July of 1882 and went on a monumental ten-day alcoholic binge, which climaxed when he sat down under an oak tree, drew his gun and used it to commit suicide.
The original story was written by William Bowers and André De Toth with John Wayne in mind. Wayne loved it and offered Bowers $10,000 for it. The writer thought it was worth more and told Wayne how he felt. The actor reportedly said, "Well, you wrote it for me. Don't you have any artistic integrity?" Bowers later got $70,000 for it at Fox, and Wayne harbored ill feelings about the incident, accusing Bowers of selling it out from under him. In addition, Wayne refused to work for Columbia Pictures because its chief, Harry Cohn, had mistreated him years before when he was a young contract player. Cohn thought Wayne was seeing a woman Cohn himself was having an affair with and tried to ruin Wayne's career. Cohn had bought the project for Wayne, but Wayne's grudge was too deep, and Cohn sold the script to Twentieth Century Fox, which cast Gregory Peck in the role Wayne badly wanted but for which he refused to bend. When the Reno Chamber of Commerce named Peck the top western star for 1950 and presented him with the Silver Spurs award, an angry Wayne said, "Well, who the hell decided that you were the best cowboy of the year?" Wayne's final film, O Último Pistoleiro (1976), is very similar to this film.