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 masked ball scene, St. Ives grabs a party goer and steals his mask which you then see him putting on. It is a gold mask without any markings that covers most of his face, but a few moments later when St. Ives dances with Flora, he is wearing a much smaller gold mask with black decorative markings.
Factual error: In the scene where Cinderella is in her new room at the Prince's castle, the roses prominently displayed in the foreground are brightly coloured Hybrid Tea roses (the pointy ones) which were not bred until the early 20th Century. In the 1700s (panniered skirts and powdered hair) the roses would have been of looser formation, with softer colours, e.g pink or cream cabbage roses. (These roses also appear in later scenes.)
Revealing mistake: During the scene when David is fighting off the large beast in the arena, there is a shot where you are looking right down its throat. Inside the "creature" you can see a light emanating from inside the mouth of the suit, probably so the actor inside could see while acting in it.
Factual error: When a Rear Admiral and Captain are walking together, the Captain's epaulets are the wrong way round. A cardinal sin in the Navy. (01:30:00)