Train in movie DR. Zhivago

[Tyke]

The character Strelnikov in "Doctor Zhivago" roars through one scene in a two-car train pulled by a red locomotive. Was that a real train, or one with fake plywood sides?

Tyke

[SteamGene]

I'm sorry, Comrade, but if I told you that, I'd have to hand  you over to the NKVD.
Gene

[Pacific Northern]

Most interesting question. I found a source that indicated the following:

Since the book was banned in the Soviet Union, the movie was filmed largely in Spain over ten months,[1] with the entire Moscow set being built from scratch outside of Madrid. Most of the scenes covering Zhivago and Lara's service in World War I were filmed in Soria, as was the Varykino estate. Some of the winter sequences were filmed in Finland, mostly landscape scenes, and Yuri's escape from the Partisans. Winter scenes of the family travelling to Yuriatin by rail were filmed in Canada.

....Its a start.

[Woody Elmore]

The close up scenes of Yuri and family going to Siberia were done in Spain. There is a myth that a woman extra fell under the train and was killed during filming. The assistant director, Pedro Vidal, is often quoted when he rebuts the myth. You can see the woman fall; it was left in the final cut.

Some of the external scenes of the train moving were shot in Canada. I remember seeing an article about Strelnikov's train - it may have been in Trains Magazine. 

By the way, this movie was panned when it first came out in 1965 but now is considered a classic. It might have been a better film with different and more seasoned actors.