Operation Dunkirk

The premise of the film is that a squad of BEF soldiers are sent back into Nazi occupied France instead of evacuating at Dunkirk. This sets the movie in 1940. In one early scene, the BEF squad are riding in a Jeep with a white star on the hood indicating it's an American vehicle, also Jeeps weren't built until 1941. Which is the year after this film takes place. The villain in the film wears the insignia of a Private in the SS but is wearing a Naval jacket. This same Nazi also continuously switches between speaking German and English to every one, including the Germans under his command. With all that said, the "package" they are sent to retrieve is a lady who knows how to make Radar. The movie is in 1940 remember; Radar was invented in 1933. Did any one research anything pertaining to this film? The movie is just bad. A waste of the $5 I spent at Walmart!