The consist did not have any of it's trainline airhoses coupled, and the brakes were not charged. I doubt that disabling the alerter would have done anything, as the engineer dismounted the moving train in order to throw a misaligned switch, leaving the loco in motion, unmanned, on a downhill gradient.
Wet rail, and slippery handholds, along with the train going too fast, caused the engineer to slip and fall down on the ballast, him watching the train increase in speed.
The movie has little factual basis with the actual prototype (correcrtion) #8888 runaway.