The CPR provided rail construction gangs that appeared in the film and set up a stretch of fake tracks beside the main line. The CPR also provided an authentic 1800s construction train.
Randolph Scott was 52 years old (born in 1898) at the time of this movie's release, but his love interest, Nancy Olson, was only 21 at the time (born in 1928).
The producers employed Indians from the Yiskabee or Stony Sioux tribes to portray the natives in the film.
At the beginning when Tom Andrews is in Cornelius Van Horne's private train car, there is a picture of a 4-4-0 engine. This is a print of the Western & Atlantic Railroad engine, "The General" famous for the Andrews Raid during the American Civil War. The General used to be in Chattanooga, TN, but is now housed in Kennesaw, GA.
It's the first Cinecolor film to use a post-exposure flashing technique to enable interior scenes to be shot with less light.