I just found this neat slapstick film of a replica Rocket. The engineer looks like Buster Keaton, but I can't be sure.
Possibly running the train v-e-r-y slowly, and filming at a slow frame-rate. When projected at normal frame-rate the action would look normal...???
Yes, it's part of one of Keaton's best, called Our Hospitality. It's hilarious, especially if you've ever loaded a muzzleloader. The engineer isn't Buster Keaton, but if I remember right, is his brother. I think the locomotive was built for B&O's centennial rail pageant of 1921.