Other mistake: In the scene showing Patton's arrival in London, stepping out of a Packard limousine in the night, the car shown is a postwar model year, e.g. 1948. Patton did favor Packard cars, but this one could not have existed at the time.
Factual error: During the early portions of the film, General Bradley's Jeep is a proper WWII Willys Jeep Model MB (wipers on top of windshield), but the second Jeep that follows Bradley's is a 1950-1952 Model M38 (wipers below windshield) which won't exist until five years after WWII ends. (00:10:00)
Factual error: When he is talking with General Bradley at the Carthaginian ruins near the beginning of the film and he recites his re-incarnation poem. If you look very carefully at the sky you will see a jet streaking, from left to right on the screen. Easy to miss but I've replayed it many times. The object is going in a straight line and going way too fast to be an internal combustion engine plane.
Factual error: At the end of Patton's speech in Knutsford, just when the marching band starts playing, you can see a modern (in 1970) tanker truck driving in the background for a couple of seconds. (01:55:50)
Character mistake: While General Patton is in Malta as a decoy for a fake Greek invasion, he gives some aides a tour of the fortifications there and tells them that they were "defended by 400 Knights of Malta and 800 mercenaries against a force of 40,000 Turks." He is referring to the Siege of Malta in 1565, but the date he gives is 1528.
Factual error: Patton wears two overseas service bars (one awarded for every six months' service outside the USA from 7 December 1941) until he goes to Normandy to take over the Third Army. On the plane over he is suddenly wearing four bars. He would have received his third bar before he arrived in Normandy, and his fourth afterwards.
Factual error: Bradley tells Patton that there is trouble in the Ardennes, foreshadowing the Battle of the Bulge. In reality, General Bradley dismissed the German operation as a "spoiling attack." His command was virtually annihilated by the German attack, and Eisenhower transferred the remnants to General Montgomery's 21st Army Group. Bradley was quietly sidelined and given a fourth star as compensation.
Factual error: At the battle of El Guettar, the German tanks which aren't German by the way, but they probably couldn't assemble enough Pz IV for the movie), are retreating from the battle with the rear towards the American positions, although having turned their turrets to face them. German tank crews were pretty experienced by then, and they knew all too well that a tank never should expose its vulnerable rear to the enemy, but rather retreat in reverse, having the strong frontal armor facing the enemy.
Factual error: In the opening scene when Patton addresses the troops in full regalia the medal he is wearing on his neck is attached to the ribbon by the "oak leaves and swords" of the Nazi German Knight's Cross. One of Hitler's highest valor awards presented only 160 times usually by Hitler himself, but in all instances personally approved by him. Patton did obviously not receive one. Also missing from Patton's uniform is the Silver Life Saving Medal which he received for saving a man from drowning. It was reputedly the award of which he was most proud.