Factual error: When the camera took a shot on a train coming to a station in Czechoslovakia, you can see electric cables above the train tracks. There was no such thing in Czechoslovakia as electrified trains in the 1940's. The electrification started in the 1950's. (00:01:05)
Factual error: Not long into the film, D'Artagnan jumps in some hay. There's a flag of the province of Québec (Canada) visible in the background. This film is set in France at a time this flag didn't even exist.
Factual error: During the engagement of the 20th Maine in defense of Little Round Top there is a tremendous amount of firing going on as they repel charge after charge of Confederates. Yet, there is not a single leaf, or tree branch, that falls to the ground. With that amount of lead flying around there would have been debris everywhere. There are actual Civil War accounts where whole trees were cut in half by bullet fire.
Factual error: The Germans encounter three enemy tanks, all Russian T-34/85 models that were introduced in mid-1944. Additionally, they shoot at the tanks with an anti-tank gun which is painted sand colour. This colour was not introduced until Feb 1943.