Factual error: The Germans in the castle are using Bell 47 helicopters which a) were American, not German, and b) weren't even in operation until 1946.
Factual error: The aircraft at the Oberhausen airfield at the end of the field are T-6 texan trainers of the Austrian air-force painted with Luftwaffe markings.
Factual error: In the flashback scene where the commandos are being briefed on their mission, they are told that General Carmody was on his way to a meeting with Russian officers on Crete. Hardly the best place for a meeting between the Allies since Crete was then under German occupation.
Factual error: As the coach moves through the village near the end of the film, it drives past a tracked vehicle. The vehicle is a Hotchkiss LPz, a type of armoured personnel carrier not produced until the 1960s.
Factual error: Smith has the books with names in his pocket when he goes into the water, jumping from the cable car. When he shows the books to Turner, they are in perfect shape. They should have been waterlogged or at least showed some sign of water damage.
Factual error: When General Rosemeyer steps out of the helicopter in the courtyard, he salutes Colonel Kramer. Colonel Kramer then returns the salute. A senior officer would never salute a more junior officer first. (00:28:25)
Factual error: A number of the German uniforms in this film are incorrect for this period and location. The reversible white/camouflage parkas worn by the allies were scarcely seen beyond the eastern front before D-Day and would have looked very suspicious without the matching over-pants. Additionally, the marsh pattern camouflage on these didn't appear on these until mid 1944, which only partially replaced the Heer splinter patterns, SS camo patterns, as well as blue and olive solids. Finally, the stereotypical black SS uniforms seen in the film were largely replaced with an olive green version of similar cut nearly 10 years before the film was set. In 1943-44, it was only worn by Himmler (who also wore the olive version), his staff, very highly placed members of SS related organizations, some of Hitler's bodyguard detachment, and native security forces on the eastern front (hiwi's).