Sam Elliott, Tom Selleck, and Jeff Osterhage wanted to do another western together after they did Die Sacketts (1979). They contacted that film's writer, Louis L'Amour and asked him to write a story idea for them. This film was the result.
Sam Elliott and Katharine Ross play boyfriend and girlfriend in this movie. They became husband and wife in real life, marrying on May 1, 1984.
The locomotive pulling Holliday Hammond's train is Sierra Railroad No. 3. Built in 1891 and nicknamed the "movie star engine", No. 3 has been featured in numerous Westerns, most famously in Zurück in die Zukunft III (1990).
In the book, the descriptions for Mac and Dal are flip-flopped.