The unfinished buildings that Wade and Evans run through in the climatic shootout in the town of Contention were originally supposed to be fully finished, but production ran too low on money to have them completed.
In a deleted scene (included on the DVD), Ben Wade tells Byron McElroy, "I heard that your boss, Al Pinkerton, got an infection from biting his own tongue. And he died last month. Is that true?" Allan Pinkerton did die from an infected bite on his tongue, on July 1, 1884. This would place the events of the movie as occurring in August, 1884.
The weekend before shooting was scheduled to wrap, a freak storm dumped nearly 2 feet of snow on the supposedly drought plagued town. Labourers shoveled the snow from the buildings' balconies and roofs and distributed 89 dump trucks worth of dry soil on the ground. Backhoes created an 8 foot tall rampart of snow just beyond camera sight lines for the remaining 6 days of shooting.
Originally the marshal and his two deputies merely surrendered their weapons to the outlaws in Contention. Later, the filmmakers were left with the difficult plot point of deciding what their role would be in the rooftop chase. Unable to come to a satisfying answer, they decided to contradict the original script and had them shot dead after they surrendered their guns.
Russell Crowe was director James Mangold's very first choice for the role of Ben Wade. After Tom Cruise dropped out of talks for the film, putting it into turnaround, it was the casting of Crowe that got the production back up and running.
The terse dialogue between Ben and Dan in the bar when Ben is captured is taken almost verbatim from the original film, although some of the lines have been given to the other man or its order in the conversation changed.
On the first day of filming, a rider and his horse were seriously injured in a scene when the horse ran directly into a camera-carrying vehicle instead of veering off as planned. The rider was hospitalized, and the horse had to be euthanized on the set. The animal's death prompted an investigation from the American Humane Association. By November, the AHA concluded its investigation, finding that the horse did not respond accordingly due to having received a dual training approach and the rider not being familiar with the mount. The organization recommended no charges against the producers.
Dan Evans uses a Spencer carbine chambered for .56-56, a Colt 1851 navy revolver with a Richards-Mason conversion to fire cartridges (identical to the revolver carried by William), and a Remington 1889 sawed off shotgun. Ben Wade uses a Colt 1873 single action Chambered for .45 Long Colt, with a gold crucifix inlaid in the ebony grips. Charlie Prince carries two 1869 Smith and Wesson Schofields, chambered in .45 S&W, with custom cross-draw holsters. Byron McElroy carries the same 1889 shotgun Evans later uses. The coach in the beginning of the movie is fitted with a Colt Gatling gun, and the two shooters inside have Winchester 1873 rifles chambered in .44-40 caliber.
When doing a 2013 adaptation of the play "Orphans" on Broadway, Alec Baldwin visited the Criterion Collection, which restores classic and contemporary films for home video. Baldwin went to their Criterion Closet, which houses all the current in-print titles that the company keeps in stock. The actor picked up a blu-ray copy of the original 1957 film for "Orphans" co-star Ben Foster, who co-starred in the 2007 film.
According to comments made by Ben Wade about Al Pinkerton's death in July 1884, this would place the movie to be taking place in August 1884. This may not be true, however as the shotgun that Byron, and later Dan uses was not in production until 1889.
The trivia items below may give away important plot points.
The film's ending is vastly different from the original. In the original film, it was Evans' wife that accompanies him and Wade, not his son. Also, in the original film, Wade and Evans successfully board the train after shooting down the other outlaws, whereas in this version, Evans is fatally shot by the outlaws (whom Wade executes in retaliation). Wade gets on the train, but whistles for his horse shortly after sitting down