Revealing mistake: Rock Hudson angrily picks up Doris Day from her bed, blanket and all, and carries her through town to his apartment. When he is walking down the sidewalk, the blanket slips and the supporting wooden board underneath Doris Day is visible. This made carrying her easier.
Continuity mistake: The background shots of the Matterhorn show it with a clear sky, then a cloud around it, then a clear sky again. This keeps happening.
Continuity mistake: After Sir Hugo has stabbed the girl on the moor, no blood is visible on the knife he used, however after he drops it (because he is attacked by a hound) blood has now appeared on it.
Other mistake: When the Behemoth swims up the river & capsizes the ferry, a static model is used that bears no resemblance to the animation model seen throughout the film.
Continuity mistake: When Molly (Sandra Dee) grabs the letters she had hidden in the suitcase under the bed, her dress is still unzipped in the back. After ranting at her mother for having read the letters, she throws them into the fireplace, only now her dress is completely zipped up.
Continuity mistake: In the start of the movie Charles says that he has got a letter from his aunt in Italy. But she lives in Brazil, and you don't hear anything about his aunt being on vacation to Italy.
Factual error: The movie takes place "somewhere in the South Pacific, 1942", yet the transport plane taking LTJG Braden to Hawaii has post-war markings.
Continuity mistake: The doctor just killed Mr. Fleming. Cut to Agnes Moorehead playing cards; She is casting no shadow on the desk from the side view, but in the view with the camera in front of her, she is projecting a shadow. (00:11:35)
Continuity mistake: When Dapper takes Woody out of the tree after Woody's hiccuping distracted him, he is holding Woody with his right hand. In the next shot, Dapper is now holding Woody in his left hand.
Continuity mistake: When Elvis hands a pair of binoculars to his pappy, you can see there is a swarm of flies buzzing around Pappy, but in the next shot the flies have disappeared.
Continuity mistake: The numbers of the Mescalero raiders that attack the party change repeatedly throughout the scene. There are 10, Ben shoots one down, there are still 10 when he drops another one, he kills a third, still 10 attack, and so on. (00:28:30)
Other mistake: A police officer fires two shots, hitting a bank robber in the back. The "bullets" do not make holes in the robber's coat. All they do is create two tiny puffs of dust.
Continuity mistake: In the opening scenes, the panoramic view of the Larkin homestead shows Lorenzo's "Gummint" Ford sitting with its hood up, days before he has been assigned to the case.
Continuity mistake: Susie, a six-year-old girl, leans over a bathtub and reaches for a rubber duck. She falls into the tub but it obvious the tub has no water. (The actress, Terry Burnham, landed on a pad or cushion.) Immediately after she falls, there is a very noticeable jump in the film. Then water splashes up but the splash is much too high to have been made by the little girl. The next scene shows the mother entering the bathroom and the little girl, now completely drenched, standing up in the bathtub.
Continuity mistake: Daffy takes down a gun from the mantle, but when Daffy points it at Bugs in the next shot, you can still see the gun on the mantle.
Factual error: It appeared that, during the engagement with the Serapis, every hit by either ship's guns resulted in an explosion and fire. Unfortunately, explosive shells wouldn't be used on shipboard (aside from bomb vessels) until the next century.
Continuity mistake: When Bugs is performing his shooting stunt in the saloon, you can see the entrance behind Sam has nothing between it. When Sam tells Bugs he's missed, we cut to Bugs who says "Wait!" and then return to Sam, and this time there are doors between the entrance.
Deliberate mistake: For all exterior shots on the surface of Mars, the crew's "pressurized" space helmets have no face-plates (their faces are fully exposed to the hostile Martian environment). The transparent face-plates they intended to use reflected far too much studio set lighting, such that the glare would have obscured the actors' faces. On a $200,000 budget and a 10-day production deadline, they simply scrapped the face-plates and shot the scenes with wide-open helmets.
Continuity mistake: When Sylvester is looking through the window with his binoculars, he looks at Spike and you can see there is a bowl with a bone next to his kennel. But when Sylvester sneaks past Spike's kennel after entering the yard, the bowl has gone.
Revealing mistake: Near the beginning, when police Lieutenant Rowan is inquiring on the death of Ken Drake, there are only 4 men in the room, all facing one another in a wide shot. The camera cuts to a close-up of Dr. Bradford for a couple of seconds, and there is a distinct puff of cigarette smoke passing behind him, but none of the characters in this scene are smoking. Lieutenant Rowan does smoke later in the film (in fact, he's the only character who smokes), but he's not smoking in this early scene. Apparently, the close-up of Dr. Bradford was borrowed from omitted footage in which Lieutenant Rowan was smoking.