The first director attached to this subject, several years before the film was finally made, was Joseph Losey. He had wanted to cast Lena Horne in the role played by Ruby Dee, which originally was planned as a much larger part.
This film bombed at the box office, resulting in a loss to MGM of $608,000 (about $7.04M in 2023) according to studio records. It did not even make back its negative cost, let along expenses for duplication, distribution and advertising.
Victor Kilian is listed as the Flyer's engineer (although uncredited in the movie). Although the movie was made years before everyone involved in the production, down to and include the caterers, was given some credit, the actual train engineer in this movie is, in fact, Paul W. 'Pat' Durnell. He was an employee at MGM (Lowe's Inc) from the early 1930s until his death in 1954 at the Motion Picture Hospital in Woodland Hills, California. Over the years, he worked in the prop (construction) and special effects departments and was the resident steam locomotive engineer for MGM Studios. In several scenes he is visible but barely recognizable from the front. However, there is one scene taken from the back of the cab looking forward, where the back of his head and his easily recognizable ears are clearly visible. Durnell also drove the train in The Harvey Girls (1946).
Character actor Will Geer was blacklisted for refusing to testify before the infamous House Un-American Activities Committee soon after this movie was made in 1951. He would not appear in another Hollywood sponsored movie until 1962.
In 1861 the train would have traveled on a number of different short line railroads to get from New York to Washington (the Philadelphia & Trenton, the Philadelphia, Wilmington & Baltimore, the Baltimore and Washington, etc.); the Philadelphia, Washington & Baltimore Railroad was not formed until 1902, and it was still in existence (on paper) until 1976. Obviously the filmmakers kept the name consistent to provide continuity and to avoid having to repaint the engine and cars after every few shots.