Factual error: The final scene of the movie has Col. Kirby and the little Vietnamese boy supposedly on the beach at Da Nang, Vietnam. Kirby is saying, "The future of 'nam is you, kid", and the camera pans out to the sea and the sun is going down. The sun's sinking in the east...
Suggested correction: Nowhere in the film are we told where in Vietnam the Green Beret base is, just that it is in South Vietnam (of course). South Vietnam has a Western coast, along the Gulf of Thailand, along which anyone can watch the sun set over the sea.
Factual error: The Germans in the castle are using Bell 47 helicopters which, apart from being manufactured by the enemy, did not even appear until after the war.
Factual error: When the hitman shoots the Mustang's windshield, the damage is not consistent with a shotgun blast at close range. The windscreen is actually hit in two separated areas. Winchester would be very unhappy if their guns really shot like this.
Factual error: It seems unlikely that the bullet hole in Harmonica's jacket should have burned edges - he was shot at a distance of more than ten metres. (00:36:35)
Factual error: "Ice Station Zebra" is one of dozens of films which make the mistake of showing people carrying rifles such as M-16s with the magazines inserted. In the scene where Marine Captain Jim Brown arrives at the submarine via helicopter, he comes aboard passing his M-16 through a hatch with the magazine inserted, barrel first - a double safety violation. I first saw the movie in a Marine Corps base theater, and all of us yelled at the screen when we saw that.
Factual error: The German tanks are American M47s, post WW2. They had the same hulls as the M46s (also post-WW2), but a better slope and greater effective armor on the turrets.