Continuity mistake: When the German planes attack at the end, the plane firing the rockets is shown approaching the bridge, walkway, and mountain with the mountain to the left of the plane (to the viewer's right). In the next scene looking straight at the walkway on the mountainside, the rockets come the viewer's right which cannot be given the plane's approach.
Continuity mistake: When the train is taking water it is sitting on a far right spur line, but when it leaves it is on the main line.
Answer: The majority of prisoners were heading towards Switzerland through the tunnel, only a few prisoners with weapons were acting as a rear guard to hold off the German troops chasing them and buy the prisoners time to escape.
Scott215
All the prisoners were on the train. I've contended before, they didn't need to fix the track. Just leave the train on the bridge and go straight through the tunnel. That route HAD to be shorter than going around on the walkway, and they would have had a much larger head start than waiting to fix the track.
kaevanoff