Hi Russ!
"Duel in the Sun" used Virginia & Truckee 4-4-0 #22 in two scenes. One was filmed on specially laid track at the far west end of the San Fernando Valley (the armed confrontation). The other was shot near the small town of Elgin on the Southern Pacific's line between Benson and Patagonia, Arizona. There was also a wreck scene using Sierra Railroad 2-8-0 #18 that was filmed about a mile east of Cooperstown on that line. These shoots are covered in the next two volumes of the "Hollywood's Railroads" series, Virginia & Truckee and Sierra Railroad.
Buster Keaton was a rail fan who used trains in many of his films, most notably "The General," and actually had a model railroad at his home in North Hollywood prior to his death in 1966. The Rocket-type locomotive in "Our Hospitality" was built for that film in 1923 and was also used in another well-known silent film "The Iron Mule," in 1925. The train scenes for "Our Hospitality" were shot on the narrow gauge line between Truckee and Lake Tahoe, California.
Any Keaton film is worth watching, as he was one of the true masters. I also highly recommend Harold Lloyd films, many of which contain trains or streetcars.
"Duel in the Sun," on the other hand, was intended as David O. Selznick's epic follow-up to "Gone With the Wind." I watch "DS" every ten years or so, trying to give it another chance and find some redeeming social value, but I cannot warm up to that film. I've given "Raintree County" (featuring the B&O 4-4-0 "William Mason") the same chance several times over the years and come away cold every time. Some films are good and some just don't work.
Thanks for letting me pontificate!