Factual error: During the scenes with the armored train, a USATC S100 can be seen. This should not be possible as the S100s were American locomotives sent to the Allies during the war and would not have been in France at the time. They only arrived in France after WW2.
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.






Answer: In several location throughout France, from Paris to Mertz, with many scenes being filmed on location. You can find more details on IMDB or Wikipedia.
Bishop73