Greetings:
I saw part of this movie as well. I changed the channel to this movie just before the train was pulling into the "Apache Wells" station. The train was indeed the Southern Pacific narrow gauge Owens Valley line. I did not get a good look at the locomotive, but it was an ex-Nevada-California-Oregon Ry. 4-6-0 with a semi-cylindrical ("whaleback") tender.
The real gem in the train was the last car, the caboose (looks like a combination passenger-baggage car) No. 400. This is a Carter Brothers duck-billed car, now preserved at Ardenwood, California. See page 65 in "Slim Rails through the Sand" by George Turner, or page 217 of "Southern Pacific Narrow Gauge" by Mallory Ferrell.
There was another railroad sceen at the end of the movie, but it was standard gauge. It looked like the Sierra Railroad to me....
This movie was not mentioned in "The Movie Railroads," by Larry Jensen.
Tom Armstrong