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.
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.
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)
Factual error: The U.S. Paratrooper uses his "clicker", and the German answers with a "double" click-click - click-click. The Paratrooper stands up, and the German soldier shoots twice with his Mauser K98 without pulling back the bolt between shots, which is impossible.
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.
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.
Factual error: So the Civil War ends, and the colonel heads for Texas. It must have taken close to a decade to arrive there, for when he rides into Blackthorne, Texas, he's packing a Model 1873 Colt, and a Model 1873 Winchester.
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.
Continuity mistake: Gabriel writes in his letter that his friend was killed at Elizabethtown, but you can see that the letter actually states he was killed at Monmouth.
Factual error: In the scene where the king attempts to seize the five members from Parliament, Cromwell makes a dramatic refusal to leave and proposes various "Laws" to prevent his arrest. Cromwell was not one of the five members whom the King tried to arrest and no law can come into force until it had been signed by the reigning Monarch anyway.