I am quite a bit of a train nerd, and am curious about how the film did the locomotive scenes.
I am not sure if that is a real engine though, I don't see any brakes on it! Not to mention the train lacks the 'link and pin' or the knuckle couplers used to connect American trains of the era. Despite this it looks like a rather accurate representation of a real train locomotive, being a 4-6-0 (Ten-Wheeler) type which was used in the era the film is representing. Here is a latter era, yet similar locomotive: Steam Locomotive Information
It should be noted Disney has a long history of designing realistic looking train locomotives, just look at the C.K. Holiday and the E.P. Ripley which are both old style operating steam engines built in 1955! Not to mention Ward Kimball did the paint design for the two engines at the Golden Spike Monument in Utah. Disney has shown they can make great replicas of old time trains.