Factual error: Joseph Cotton spends the second half of the movie trying to get out of Canada, but in the scene at The Cave of the Winds with Jean Peters, he must have forgotten that he was already on the American side of the falls. (00:54:00)
Factual error: The Marines that arrive at the landing site are said to be from El Toro, but El Toro was a Marine Corps Air Station; it would not have had the infantry, artillery, and armored units that arrive at the site.