Factual error: When Hack's train is rushing to get onto the siding before the mail train hits his, there is no-one to open or close the switch, and the switch is not connected to an interlocking tower. (00:56:00)
Continuity mistake: When Shack and A no 1 fight in the train, almost at the end of the film, Shack tries to strangle A no 1 with a chain. A no 1 puts his left hand on Shack's chin with straight and separated fingers. In the next shot the hand of A no 1 is grasping the mouth of Shack with his hand in fist and tight fingers. This repeats twice between shots. (01:53:00)
Revealing mistake: In the final scene where Cigarette gets thrown off the train you can see the stunt double stepping off a box before jumping out of the rail car. (01:58:35)
Factual error: On the night of 19 October 1933 the railroad workers begin betting whether A-One will make it to Portland on the 19. A quick closeup of the money changing hands reveals the $1's to have the Great Seal reverse (introduced in 1935) plus the motto IN GOD WE TRUST (introduced in 1957). Also, the green-seal Federal Reserve Notes and the red-seal United States $2 notes are of the types first introduced in 1934.
Continuity mistake: During the fight between A no 1,and Shack. Shack is cut with the ax, the ax head is coated with "blood," as A no 1 is setting up for another swing you can see the ax head behind his head, it is still "bloody," but as he starts the swing, the ax head is shiny and clean, and then it's bloody again.
Audio problem: In the scenes aboard the train, you can hear the railroad crossing signal. But in the scene there is no road or highway crossing the tracks, only forest or open field. This happens al least 8 times along the film.
