Three train scenes are taken directly from Les conquérants (1939) - the race with the horse-drawn stagecoach along the tracks; the burning carriage and subsequent escape on horseback; the triumphal arrival of the train in town at the end.
When Joe Castro is gunned down, he falls against a sign advertising French Dry Cleaning. Dry cleaning was developed by French dye works operator Jean Baptiste Jolly, who accidentally spilled kerosene on some cloth and noticed that spots on the cloth disappeared. He opened the first dry cleaning business in Paris in 1845, using a combination of kerosene and gasoline. This is likely the process in general use at the time this film is set. In Le dernier des géants (1976), set in 1901, Bond Rogers convinces J.B. Books to have his suit cleaned using "dry process cleaning" that uses naphtha. The risk of fire led to government regulation of dry cleaners, who switched to less flammable solvents after World War I.
This film is set in 1875-6. The real-life Fort Worth Star newspaper would not be founded until 1906. It would combine with the Fort Worth Telegram to become the Star-Telegram, and it still published as of 2022.
The first train arrived in Dallas, about 32 miles to the east of Ft. Worth in 1872. It took another four years for a railroad to be built to Ft. Worth in 1876. As one sign in the Panther Club parade states, "Lay the steel in '75, '76 ride in style".