Plot hole: Radl and Steiner discuss the entire scheme to kidnap Churchill on the Alderney docks - in full view and hearing of a number of civilians (who shouldn't be there, pace another posting), including local fishermen. Though the Germans banned all fishing activities in the Channel islands including Alderney in 1941, they were well aware that there was a flow of information from the island to military authorities in the mainland. Why would they be so stupid as to discuss a top secret military mission in public? In reality, they wouldn't even discuss it in front of their own men.
Col. Max Radl: Your meeting went well? The Führer had something specific in mind?
Admiral Canaris: A simple exercise in logistics, nothing very complicated: he merely wants Winston Churchill brought from London to Berlin. And we are ordered to make a feasibility study. Today's Wednesday. By Friday he will forget it, but Himmler will not.