Archer is variously referred to as Chief Superintendent, Superintendent and Inspector.
According to SS General Kellermann, Standartenfuhrer Huth is from the Reichssicherheitsdienst (Reich Security Service), but Huth does not have the correct SD badge on his left sleeve between the cuff title and the elbow.
Standartenfuhrer Huth is wearing the Knights Cross incorrectly. Worn at the neck, it should hang down slightly on a link from its ribbon and be between the collar and not over it.
Standartenfuhrer Dr Huth's shoulder boards have blue underlay. Sicherheitsdienst shoulder boards use the police design with a black underlay. He correctly has a medical symbol on his boards denoting that he is a Doctor.
In the opening credits the animation shows a German raid (presumably during the Blitz) consisting of Bombers and fighters, of which the tail-plane is characteristic of the BF109. The only variants of this plane at the time had central, either propeller or above engine guns, or externally mounted pods for single guns or cannon under each of the wings. The animation during the beginning credits shows gun flash from the German escorting fighter as it engages the Spitfire coming from the wing itself, as per the eight gun (four per wing) of the British aircraft's Browning 303's.
It appears that Standarten Fuhrer Huth is in fact wearing an Iron Cross first class, this medal should be worn on the left breast pocket and is secured with a screw stud on the back whereas the Knights Cross hangs from the neck on a ring with a ribbon around the wears neck. One assumes the costume department could not find a knights Cross.
Jaguar didn't exist as a car brand until 1945.
The aircraft in the opening scenes is a Griffin-powered machine with a four-blade propeller. The first of these didn't appear until 1942.
Archer introduces himself to Barbara Baga as Chief Superintendent, however that rank was not introduced into the Metropolitan Police until 1949.
Dr. Huth wears what looks like an Iron Cross, 1st Class, fastened rigidly where the top button of his tunic would be. No Nazi medals were worn in this manner. Medals like the Knight's Cross and War Merit Cross hung around the neck on ribbons. Furthermore the Iron Cross 1st Class was worn on the left breast (Huth wears one here as well.)