The cabin featured in the first act was specifically built for the movie. Peter Hyams decided to build it on top of a mountain in that particular spot while it was still covered in winter snow. After the snow melted, it turned out that the spot was a dump and it took a short while to clear it out.
Writer/director Peter Hyams was searching through old movie classics that might be good to remake but only ones which were not too well known and significant. In the end, he chose Richard Fleischer's The Narrow Margin (1952).
Much of the footage of the film's helicopter chase and early train sequence was reused in the 2000 film "Crash Point Zero" (aka Extreme Limits), starring Treat Williams.
According to the Train Movies website Railserve, "The film was shot in British Columbia, where a 'Lac Des Arcs' train station was built along the tracks specifically for the film. The train consisted of a British Columbia Railway (BC Rail) SD40-2 diesel and 12 privately owned passenger cars, all painted in VIA Rail Canada livery to appear as the Toronto-Vancouver Canadian. The private cars included one dormitory, one baggage car, three coaches (#521, 524, 550), one dome car (#555), one dining car (#548), another coach (#540), three sleepers (#558, 564, 544), and a rear dome car (#597). The primary compartments in the film are A6 in #564, and later C6 in #558. Some of the distant exterior shots of the train (specifically two bridge crossings) were filmed using a model train."
The movie's central character portrayed by Gene Hackman is called Robert Caulfield and is named after director Peter Hyams' former manager at a television station. Elliott Gould's character in Capricorn One (1978) (also directed by Hyams) has the same character name of Robert Caulfield.