Factual error: Lieutenant Hudner comments that he went into the Naval Academy right after Pearl Harbor. Pearl Harbor happened in December 1941 and he couldn't have gotten into the Naval Academy until 1942. Then he says, "The war ended a month before he graduated." The Naval Academy is a four-year school. That means he wouldn't have graduated until 1946, a year after the war ended.
Factual error: The parachute flare was not invented till 1922. This film takes place in 1918 but features one. (00:21:15)
Factual error: The tank used by the German platoon is a Soviet T54/55, which didn't come into service until 1948, after the Lapland War had ended.