When Benton throws down the bottle of explosive on the bridge, the explosion occurs around 2 metres/ 6 feet from where the bottle smashes.
When Major Benton gets off the train the first time, the sound of air brakes is clearly heard. However, the Westinghouse air brake was not invented until 1869, five years after the action in the movie occurred.
Sherman's March to the Sea is mentioned, though it didn't begin until November, 1864, one month after this story takes place.