Question: In the film, Manny is in jail for safe-cracking and Buck is in for statutory rape (he didn't know the girl was underaged). Aren't these crimes pretty minor for both men to be in a dangerous maximum security prison in Alaska?
Question: How was Sara so sure that there was no engineer on the train, considering that she was not able to get to the front carriage to find out?
Chosen answer: Most likely from the speed at which the train was going, a train is like driving any large vehicle. You have to maintain a certain pace, to stop at an instant, for the unexpected.
Question: Why would the loco derail if the siding switch was set to the siding where the freight train went?
Answer: It wouldn't derail, it would break the bolt on points - the part of switch that moves, causing the points.
Question: Why didn't they go back to the 3rd or 4th locomotive where they could access the brake hoses and disconnect one of those, instead of trying to get to the hoses between the 1st and 2nd engines?
Answer: That's what they were doing, going car to freight car break the hoses. They knew it would slow the train down but not stop it. Slow enough so they could jump off without getting injured. That's why they were desperate to get to the first engine not only to break the hose but disconnect from it.
Answer: Manny is a career criminal. He's been in and out of prison his whole life. That latest crime was his last straw. He is beyond rehabilitation. Besides, he and the warden butted heads during his sentence. Manny was getting a following, and the warden reminded him who was in charge. Which is why he was welded into his jail cell. As for Buck, statutory rape, an underage girl. He's been labelled a rapist, child molester, and put on the sex offender list for life. The standards have not changed.