Factual error: Late in the film, Nicolas Cage throws a grenade to kill the Japanese who have captured Roger Willie. The resulting explosion is a prolonged pyrotechnic plume with petroleum flames bursting out of the ground. WWII grenades didn't produce flames of any kind, and they still don't.
Factual error: Throughout the film, Joe Enders is wearing an M1 Helmet. But his helmet looks like a non-WW2 type and possibly Vietnam era. From the side of the helmet, it is a higher cut along the sides. This is a usual indicator to the era of the helmet, as WW2 M1 helmets are lower along the ears for better protection.
Revealing mistake: When Christian Slater and Roger Willie play a mournful Indian tune in a recorder/harmonica duet, neither actor knows how to play his instrument, and it shows.
