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.
Factual error: As the British prepare to march inland following the capture of Sword Beach, Lord Lovat tells piper Bill Millin to play "The Bluebells of Scotland," but Millin instead plays "The Black Bear." Additionally, he can be heard playing the same tune during the landing, but the real Bill Millin did not play that song on D-Day.
Factual error: The ribbon of Richard Burton's Distinguished Flying Cross is on upside down. The Air Force Cross following it is the right way up. The stripes on both should point the same way, as they do on the uniform of his colleague in the mess. Nobody would be allowed to get away with a mistake like this - another officer or senior NCO would soon point it out. In addition, as a long-service veteran (his colleague says he served in the Battle of Britain) he should be wearing the ribbon of the 1939-1944 Star (as it was then), which was issued to all qualified personnel from 1943.
Factual error: In the scene where Ike and the other leaders are deciding to either invade the next day or postpone the invasion, a jet plane can be heard loudly passing by through the open window. The only jet aircraft in service in the UK was the Gloster Meteor, which was developed in top secrecy; its first flight over London was on 21 July 1944, some six weeks after D Day.
Other mistake: In the early part of the movie, Rommel is addressing his Officers on the Atlantic Wall. The "mid-shots" and "close-ups" are shot against a back projection. Rommel turns to view the sea/horizon and the view is exactly the same as their "mid-shots". The effect is a horrendous "jump-cut".
Factual error: The landing craft bringing the troops ashore have PA-44 on the side. USS Fremont was in fact in the Pacific at the time, participating in the Saipan landing 10 days after D-Day.
Factual error: Before Obertsleutnant Priller and Unteroffizier Wodarczyk attack the allies, the stock footage shown is incorrect. In reality, they flew FW-190's on that mission.
Factual error: The paratroopers in the film are wearing infantry boots, i.e., short ones with a buckle-on ankle-protector rather than a one-piece that protects the ankle from breaking on impact.
Continuity mistake: Shadow of the dolly against the smoke of battle during the invasion of Omaha beach. The direction of the shadow and the geography of the beach indicate that this scene, while set at dawn, was filmed in the afternoon.
Factual error: When one of the Paratroopers gets hung up on a church roof, he reaches for what should be an M3 Trench Knife on his right boot. But if you look closely, it appears to be an M1 Carbine bayonet. This is not only the wrong knife, but M1 Carbines didn't have bayonet lugs until late 1945, if not until Korea.
Continuity mistake: Sgt. Fuller's stripes disappear (actually one stripe is hanging from his uniform) as he is running with the detonation wire. They reappear in perfect place when he is about to detonate the first charge.
Factual error: When John Wayne has a compound fracture diagnosis, the medic looks at John's foot with an uncovered light. Medics and soldiers were trained to use rain coats or anything available to block any light that they needed to use, to avoid drawing enemy fire. Furthermore, a compound fracture is supposed to mean that broken bone is protruding through the skin. John Wayne's skin is intact.
Continuity mistake: The German General Pemsel says, "Wir haben starke RADAR-storungen," which means "we have strong radar interference." In 1944, the word "radar" was not used in Germany, and quite likely not even known. The Germans used a comparable system, called "FunkmeBgerate," which basically means "radio measuring equipment."
Factual error: In the scene that introduces MG James M. Gavin, the wings on his uniform appears to be the Senior Parachutist Badge (official term for the wings), which has a star just above the parachute. The problem is that the Senior and Master rating was not approved until 1949 by the Department of Army.
Factual error: The film exaggerates the carnage at Ste Mere Eglise. In this battle sequence, the U.S. paratroopers of F company (from John Wayne's battalion) of the 82nd airborne are mown down like ninepins as they parachute into the square of the village which is swarming with German troops. In reality, only about thirty troopers landed in or around the square and less than a dozen were killed or wounded, not the whole company as the film suggests.
Factual error: In one scene, two British paratroopers mistakenly land in the courtyard of the chateau where one of the German generals is staying. The film depicts the two paras being overwhelmed and captured by up to a dozen heavily armed guards. This event did occur but it was actually just one of the general's middle aged staff officers with a pistol who successfully rounded up the two paratroopers.
Continuity mistake: When Wodarczyk and Priller bombarde the Gold-Juno Beaches, the barren beach - devoid of men, vehicles, etc., is visible in the overhead shot, just past the small strip of beach used for the shoot.