Sharps Rifles are now so inseparably related to this film that they are commonly nicknamed "Quigley guns." Sales for such weapons increased by over 1000% following the film's release, especially in the United States and Australia, and continue through 2013.
Three Sharps rifles were built for the film: one for shooting, one as a club in the fight scenes, and a back-up weapon in case one was damaged. Tom Selleck requested to keep the 3 rifles built for the film. He had two of them reconditioned to remove scratches and straighten and tighten some of the moving parts. Years later, he signed and auctioned 2 of them as part of a fundraiser for the National Rifle Association, of which he is a national board member. Selleck donated the third rifle, with its fringed leather scabbard, and belt knife to the Brownell's Family Museum.
The film was to have been Steve McQueen's follow-up to The Hunter (1980), but he fell ill shortly after making that, so the project was scrapped. It was revived several times throughout the 1980s, with various stars in mind for the lead. Harrison Ford was offered the lead role, but turned it down because he considered it too visibly similar to Indiana Jones. The lead was first offered to Tom Selleck in 1985. He had to turn it down because of his commitment to Magnum, P.I. (1980). When the series concluded in 1988, he quickly asked if the role was still available, and accepted it. The producers spent another year gathering a reasonable budget.
Quigley's ability to shoot accurately to over 1200 yards (1.09 kilometers), with iron sights, is not as far-fetched as it sounds. In 1874, during the Second Battle of Adobe Walls, in northern Texas, William Dixon used a .50-110 Sharps to shoot a Native American off his horse from 1,538 yards (1.4 kilometers). Such a heavy bullet propelled by black powder would have a trajectory similar to that of an arrow fired from 100 yards, striking its target at a 30-degree down angle. Dixon claimed his shot was pure luck.
Matthew Quigley's gun is a replica model 1874 Sharps Buffalo Rifle, built by Shiloh Rifles of Montana. They are chambered in .45-110, which is a .45 caliber bullet propelled by 110 grains of black powder. This round was the most accurate and powerful in the world until the advent of smokeless gunpowders.
According to show-business trade-paper 'Variety', the "script was written for 'Steve McQueen' in the 1970s, then developed in 1984, Rick Rosenthal to helm; project was reactivated in 1986 with Lewis Gilbert scheduled to direct". In the end, the movie starred Tom Selleck and was directed by Simon Wincer.
The evil British officer in this movie is Major Ashley-Pitt. The first Ashley-Pitt to appear in the movies was David McCallum's character in The Great Escape. That Ashley-Pitt was a Royal Navy aviator, with the rank of Lieutenant Commander. A major and Lt. Cmdr. are equivalent ranks.
While discussing the colt army revolver during the dinner in Marstons house, Quigley quips that "God made all men. They say Sam Colt made them equal". This is a paraphrase of the post-civil war slogan "Abe Lincoln may have freed all men, but Sam Colt made them equal".
Harrison Ford was offered the lead role but turned it down. This is a reversal of fortunes as Tom Selleck was the original choice to play Indiana Jones but had to turn it down due to filming Magnum P.I.