Factual error: The Germans encounter three enemy tanks, all Russian T-34/85 models that were introduced in mid-1944. Additionally, they shoot at the tanks with an anti-tank gun which is painted sand colour. This colour was not introduced until Feb 1943.
Factual error: There's no way that that mail truck would be driven along Highway 1. Choosing that route more than doubles the drive time, turning a six-hour drive into 12-15 hours. They'd take Highway 5, which is fastest but boring for filming purposes.