That battalion of soldiers our courier comes across....(Spoilers)
Something that doesn't seem realistic at all, with regards to that group of soldiers (led by Mark Strong's character) that finds the surviving courier (after the German kills the other guy with a knife). Sure, they offer him a ride part way to his destination. However...if that courier had clearly explained to Mark Strong's character what his orders were (and how many lives it would save).....why, once they get to the fallen bridge, would they let the courier go off on his own, on foot.....in enemy territory, rather than offer to have a couple soldiers accompany him??? He didn't stand much of a chance the way they left him at that bridge.