Factual error: Near the end of the movie, the prisoners are on the front of the locomotive with the German officer. The colonel is in the cab with the engineer and says "10 miles an hour, no more." Germans use metric - so the speed should've been given in kilometers per hour.
Continuity mistake: Le Bic only dismantles one rail, but when the train drives over both rails spread.
Continuity mistake: Le Biche uses a pair of pliers to get the pipe out, but as he pulls the pipe out they vanish.