When the four Nazi escaped prisoners show up, three of them wear overalls with big letters of PW on their backs. Actor Kurt Kreuger is wearing a military uniform which would never have been allowed. All prisoners would have either PW or POW on their backs.
At the start of the movie Philip narrates his story. He starts off stating that his country of the Netherlands had just been liberated and he had come to the US to enter the Pacific War. But first, he had 6 week of furlough before he had to report, and he wanted to journey across the US to get to know America. Then he states that when he was in the far west, late in the year 1944, ... PROBLEM. The Netherlands were not liberated until Nazi Germany surrendered May 7, 1945. So how could he come to the US after May 7, 1945, travel across America, and get to the far west late in 1944 (half a year before he even gets to the US)? Save that of Doc Brown's DeLorean, this is not possible.