Continuity mistake: In the final fight scene between John Wayne and the bad guy, Wayne gets struck in the head, and as he falls backwards over the wagon tongue his toupee lifts off.
Factual error: When one of the men visits a doctor and learns he is terminal, the X-ray in the scene is upside down.
Continuity mistake: Before Pollyanna arrives on the train, when Jimmy Bean pushes the metal hoop down the road, two girls stop their doll carriages right beside each other and grab their dolls, but in the next shot their carriages are about 4 feet apart, which is now wide enough for Jimmy to run between. (00:01:10)
Factual error: Jack Lemmon cooks spaghetti for Xmas dinner. On New Years Eve he picks up the tennis racket, through which he had poured the spaghetti, and one piece hangs limp from the racket. It would of course, have long dried and be hard as before cooking.
Continuity mistake: When the Jeep at the head of the army convoy starts off again, after being stopped at the temporary traffic lights set up by the crooks, the external shots show the Jeep passing the traffic lights. But the next shots from inside the Jeep show them passing the traffic lights a second time.
Continuity mistake: Seymour watches in horror as the wino is run over by the train. In the long shots, Seymour's hands are waving up and down at his sides. In closer shots, however, he's holding his hands up to his face and screaming.
Continuity mistake: When Cary Grant tells Deborah Kerr to keep the door closed, she is holding a record album. As a reaction to his directive, she lowers the LP to about waist level. The camera shot changes and she's holding the LP higher again. (00:27:55)
Continuity mistake: When Sgt. Wilkins and P.C. Thurston go on patrol in the police car, it's registration number varies between scenes, from 892FPC to UUV133. (00:38:15 - 00:45:40)
Factual error: Throughout the movie, characters refer to the "Air Force", when in this time frame (1942-3) it was the "Air Corps".
Visible crew/equipment: Anita Ekberg's character and Marcello are at the top of the church tower leaning on balcony railing while looking over the city. You can easily see the "wire" attached to Anita's hat that forecasts the moment where her hat blows off her head. (00:33:15)
Character mistake: When Dean Martin desribes his writer's block to Judy Holiday, she says that she keeps sharpening his Ticonderoga pencil until there's nothing left but the "Ti," but in fact what would be left on a little nib is the "ga."
Revealing mistake: Midway through when Ian Carmichael and his girlfriend are dining at a restaurant with Terry Thomas, they are talking and looking at the menu. The table is laid with cutlery and wine glasses - ready to eat. During their conversation there is a shot of Ian Carmichael only talking and smoking but there is no cutlery and the wine glasses have been replaced by a brandy snifter, obviously after the meal. The next shot shows the whole table with the correct pre-meal setting. When they have finished the meal, the table setting is as it was in the earlier shot.
Continuity mistake: When Daffy enters Bugs' living room wearing a rabbit costume, you can see the door is plain green. But when Elmer Fudd enters to confront Daffy, the door is now divided into three sections.
Audio problem: When Merritt is arguing with her professor, she says, "We're supposed to be intelligent" but her lips are actually saying "Don't be afraid; my opinion is yes." This is the exact same shot used a moment later when she actually says this line. (00:07:10)
Continuity mistake: When Sam says "Salt? Why didn't you say so?" at the dinner table, you can see there is a knife next to his plate, but when he leaves his chair to take the salt shaker to Bugs, the knife has disappeared.
Continuity mistake: When Bugs is putting on his napkin at Wile E. Coyote's picnic, the position of his carrot changes between shots.
Revealing mistake: Louis de Funès tries to squash a bug that was alive, well and moving in close-up, but is obviously fake and still in the next shot, in a different spot from the close-up too. (00:03:30)
Continuity mistake: When Dr Jekyll enters his laboratory at the start of the cartoon, he locks the door with his key. After drinking the Hyde Formula, he turns into Mr Hyde for a short time before going back to Dr Jekyll. When Jekyll leaves the laboratory, he opens the door without unlocking it.