The real General, the locomotive stolen in the movie, is on display in Kennesaw, Georgia, at the Kennesaw Museum of Civil War and Locomotive History.
The real locomotive "Texas" is on display at the Atlanta Cyclorama and Civil War Museum in Atlanta, Georgia.
In the film there are 16 raiders. In reality there were 20 who participated in the raid. There had initially been 24, but two joined Confederate forces after being stopped on their journey down to Marietta--as Andrews had instructed--and two more simply overslept and missed the train. These four were not depicted in the film, in addition to four others who participated.
This film and Buster Keaton's 1926 comedy feature "The General" are based on the same historical incident.
The locomotive used to depict The General in the film (Baltimore and Ohio #25 William Mason) was built around the same time as The General, and had been in service during the Civil War. This is also the same locomotive used as The Wanderer in Wild Wild West (1999).