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.
Continuity mistake: In the scene where Devlin meets Molly for the first time (outside the pub) the ARP sand and water buckets on the wall are in one position. When Molly leaves the scene, just before Devlin enters the pub, the sand and water buckets have changed position. (00:43:15 - 00:44:20)
Factual error: In the aerial shot over rural Britain near the beginning of the movie, there are two modern cars visible. Too new to be early 40's models.
Factual error: When we are in the Colonel's office at the US army base there is a US flag in the corner. It has 50 stars on it, as you can tell by the pattern. There were only 48 stars on the flag during WWII.
Continuity mistake: After Kurt returns to the quay from the raid near the start, the coat of one of his men is noticeably bloodstained. Later, walking up the stairs to the pub, the bloodstain is gone. But when he pours alcohol over Devlin's arm, the bloodstain has returned.
Revealing mistake: This film has the old movie trait of Nazis having German accents rather than actually speaking in German, which is fair enough as they take up the majority of the screen time. However, not everyone adheres to this rule and there are many characters, minor and major who slip in and out of accents, and many never have them at all.
Revealing mistake: Ms. Grey's door is kicked open by the US colonel. A split second before he kicks it, though, the door mysteriously becomes unlatched from the inside. I guess this is so the actor wouldn't hurt his leg.
Continuity mistake: After Devlin has met Molly on the beach, she runs to her horse, and obviously is having some difficulty in mounting it. When the shot suddenly changes to the closeup, she is mounted perfectly.
Continuity mistake: When Steiner lifts up the Jewish girl, if you look closely, you can see the rear end of the train about 20 metres away. Yet somehow Steiner has time to ask her name, wish her good luck, set her down on one of the carriages and watch her get shot before the train fully passes him. The departing train also conveniently slows down for him to drop the girl. (00:12:20)
Continuity mistake: When Steiner is talking to the general about the jewish girl, the distance between the two men varies considerably between shots. (00:13:00)
Factual error: When Michael Caine is standing outside the village church, it is clearly visible that double yellow line road markings have been blacked out (covered up). The film is set during the war, but double yellow lines did not make an appearance in the UK until 1958, therefore it is clear that the filmakers blacked them out to avoid an anachronism.
Factual error: When Steiner meets Colonel Radl and Liam Devlin on Alderney they are watched by two civilian fishermen. The events of this film take place in 1943, but all civilians were evacuated from Alderney to the mainland in 1940.
Continuity mistake: When Devlin is thrown out the pub window, the E-Boat captain is standing behind Neustadt's right shoulder. In the next shot, he is over to his left. Radl is also now gripping the railing. (00:35:15)
Continuity mistake: When Radl is sitting at his desk and the SS man enters, his cigarette is smoking in the ashtray. In the following shots, it's not smoking. (00:21:30)
Plot hole: When the general approaches Steiner in the train yard, he says 'you didn't seem so discriminating a moment ago' implying that he saw Steiner help the Jewish girl onto the train. But this is impossible, as there was a moving train between himself and Steiner when the incident happened. For all he knew Steiner could be blameless. (00:13:00)
Continuity mistake: After Donald Sutherland parachutes into England, he walks across a cow paddock towards a gate. As he climbs over the gate, you can see there are no cows to the left of him along the fence but in the very next shot, you can see a line of cows along the fence which weren't there in the previous shot. (00:39:55)
Continuity mistake: During the early train yard scene, the weather changes between light, heavy, and no snowfall, depending on the shot. This is especially noticeable when the SS chase the Jewish girl. (00:09:20)
Factual error: When Steiner is discussing with the SS General about "difficult decisions are the privilege of rank..." he addresses him as Herr Gruppenführer (Lt. General) he should have addressed him as Herr Obergruppenführer (Full General).
Factual error: Near the end of the movie, (when Larry Hagman enters the traitor lady's house), a grenade ends up exploding at the bottom of a flight of stairs. After it goes off, an American soldier runs up the stairs, firing at the lady in an upper room with an M1 carbine: RIPPING ON FULL AUTOMATIC! (The M1 carbine was semi-automatic until the selective-fire M2 variant was produced after the war).
Factual error: When Col Steiner is imitating the American's voice over the radio he uses the words "Delta-1" or similar. Delta is part of the NATO phonetic alphabet which wasn't introduced until 1956, well after the war had ended. "Dog" would have been the correct word to use.
