When Michael Powell and the crew went on location to Ramsgate (Eastgate in the film), they sent all their luggage and equipment in cases boldly marked "Contraband". Luckily the local wartime Contraband Controllers saw the funny side and when they arrived at the hotel they found their cases had stamps and stencils all over them saying things like "Explosives", "Examined", "Condemned".
The first film that Deborah Kerr worked on. She played a cigarette girl in one of the nightclubs visited. But although she impressed everyone, her scene ended up on the cutting room floor.
Michael Powell's golden cocker spaniels, Erik and Spangle, make their first appearance on film at the house of the aunt of Mrs. Sorensen.
The British destroyer shown several times early in the movie, marked with the hull number "H11", was HMS Basilisk. She was sunk by air attack off Dunkirk on 1 June 1940. The destroyer is referred to as "HMS Leopard" in text seen on the screen, but the Royal Navy did not have a ship of that name during World War 2.
Twenty-two years before Eunice Gayson introduces herself, and Sean Connery simply replies "Bond. James Bond." in James Bond 007 jagt Dr. No (1962) - the suave, sophisticated, confident and fearless Captain Andersen Conrad Veidt eloquently introduces himself "My name is Andersen, Hans Andersen."