Factual error: Geological surveys of the Normandy beaches were carried out months before the invasion, using divers sent ashore from midget submarines, not geologists a few days before.
Factual error: The SS Officer is repeatedly addressed as "Herr Oberst". This is a Wehrmacht rank designation, and could possibly have been correct for them addressing an SS officer, but fellow SS officers would have used the correct term "Standartenführer" (without the "Herr"). On one occasion the lower rank SS officer is address as "Herr Leutnant" which is equally wrong, should be "(Ober)sturmführer"
Factual error: The agents fly to France on an American C47 from Tempsford. Tempsford was an RAF Special Operations airfield and only British aircraft flew from there, but an American Mustang Fighter and Texan Trainer are on the airfield as well as American servicemen. The Texan is in pre-war markings, and the USAAC never flew them in the UK. The C47 has "Invasion Stripes" not used until the 6th of June, and has a "Star and Bar" on both upper wings when it should only have been one.