Factual error: At the end of the movie, a Willys is shown with an inscription on the back: "Left hand drive vehicle." The scene takes place in Midway or Pearl Harbour. This inscription on the vehicle was only for the US forces in England beginning in 1944.
Factual error: After the birth of the baby, James Stewart and "Doc" Witherspoon are discussing the course of the war. "Doc" relates that he has always lived in Virginia and that his son died at Gettysburg at Little Round Top. No Virginia regiments fought at Little Round Top - only Alabama, Texas, Georgia, and Arkansas regiments.
Visible crew/equipment: When the Muslim armies approach Brendan Gleason's castle there is a side shot of the Muslims army coming to a halt. You can see the marker stake with yellow tape at the top (used during production as a mark). (01:10:10)
Revealing mistake: Near the start of the film, when Lt. Harley is watching his love interest show off by doing gymnastics on the tree limbs, several times you can see the actual pole she is swinging on, not the tree limb. (00:08:50)
Revealing mistake: In the major helicopter scene when Ride of the Valkyries is played, the actual tape isn't going over the playing heads. (00:37:29)
Factual error: Here's a big historical mistake. The character of German Admiral Lütjens is depicted overall in this film as a wild-eyed Nazi fanatic. In real life, he was distinctly anti-Nazi, vehemently protested the anti-Semitic actions of Hitler's regime, and was himself subject to intense Nazi scrutiny as he was a quarter Jewish and his wife was half Jewish. He was one of many German naval officers who fought only for their country, not Hitler.
Other mistake: After the shoot out at night the American forces are faced with a group of hostile locals, and the team are told to pull out and get in the vehicles. As they drive off we see a back shot of them sitting on the back of the one of the vehicles, but on the right hand side you can see a backpack and part of an American soldier, did they just leave him? (01:12:50)
Continuity mistake: When the main character goes to visit his friend that had been shot in Iraq, they're driving down a country road in a 2 door Dodge Challenger, but when inside the vehicle it's a Dodge Charger, which is a four door car.
Visible crew/equipment: On the beach there's a battle charge, and in the foreground you can clearly see a set of tyre tracks from the camera vehicle preceding the charge.
Factual error: As the colonel and his companions ride out of Blackthorne, Texas, they pass Saguaro cacti, which, oddly enough, only grow in the Sonora Desert, a far distance from Texas.
Factual error: As the 1st Battalion, 7th Cavalry lifts off from LZ X-Ray at the end of the battle, it can be seen that there are no more American troops left at the battlefield. However, by the time 1/7 CAV left LZ X-Ray, it had been relieved by two full battalions (2/7 CAV and 1/5 CAV). There were around 700 American soldiers occupying LZ X-Ray by the time 1/7 CAV lifted off.