गूफ़

In the film, that is supposed to be set during the civil war, all the characters are seen carrying Colt Single Action Army revolvers, also known as "The Peacemaker". The peacemaker didn't come out till 1873. That's 13 years after the civil war ended in 1865. Cowboys and all soldiers during that time would have been using 1851 Navy, 1858 Remington, or 1861 Colt Army percussion cap (black powder) revolvers. Also the star wields a Single Action Army with a brass backstrap for a handle and Colt never ever produced a model with a brass backstrap. The gun used in the movie is obviously a reproduction made by one of the three manufacturers that were in business in 1968 when the movie was made.

The evil plot is to bump off Grant and Lee before they can finalize the South's surrender. That meeting took place in Virginia, yet the whole film occurs in a desert, which wouldn't have existed within several hundred miles of the historic event they were trying to prevent..