An addendum to Earl's notes: Jim told me the story as well. He said they had set up for the big head on collision shot and a thunderstorm sprang up so they had to postpone until the next day. Both engines were hot so they had to find someone to watch them overnight. Jim's name was on the extra board and when they couldn't find anyone else they called his home and his mom told the D&RGW he was at the movies with a date. Jim said in the middle of the film the projector stopped, the lights came on, and a voice called out "Is Jim Pearce in the audience?" He responded and was told to report to work, but wasn't told what was going on except they were going up the Silverton branch by speeder.
I've tried to get Jim to write down his stories (which are numerous), but he's like a lot of people who have done things we see as remarkable, but they see it as just a job...