Visible crew/equipment: As the villagers are running away from Kong, when the mother rescues the young child, in the next shot look to the back right side of the screen. A member of this movie's production crew steps into the shot, stands there watching as the movie extras are running, and the shot cuts away. (01:17:29)
Continuity mistake: Just before Kong is gassed and captured, he picks up someone and bites his head. In a close up, he has them by the legs, then in the long shot he is biting their head. (01:22:00)
Continuity mistake: This happens in King Kong's death scene. After Kong puts Ann back down for the last time, when he's shot (in the neck area) in the wide shot, Kong's upper body and right arm lean over in front of the building's spire, with his (limp) right arm hanging over Ann. It cuts to a close-up, and now Kong's right arm is suddenly up behind the spire, with his right hand gripping that spire. (01:38:05)
Revealing mistake: In the last third of the film just after the announcement that Kong is coming, a native jumps out of his hut, loses his balance and falls by a chicken coop. His wig comes off and gets caught on the fence.
Revealing mistake: After King Kong destroys the train track of the oncoming train, in the POV shot directly behind the train operator while he watches Kong rise from the broken track, the small model's support control bar is visible at the right as it moves up and down. The next shot is a close-up of the shocked motorman, and after he attempts to stop the train, there's another shot facing Kong with the control bar visible for a moment. (01:31:50)
Other mistake: While Ann Darrow is lying on the Empire State Building ledge beside the ladder, the backdrop shows the Chrysler Building, Queensboro Bridge, and Roosevelt Island, behind to the right. However, after Kong falls from the skyscraper, when Jack appears and says, "Ann, hang on, dear," this one shot is angled toward the left of the ESB, but the set's backdrop is positioned so it's the same background with the Chrysler Building, Queensboro Bridge, and Roosevelt Island, behind to the left. (01:38:20)
Continuity mistake: When King Kong carries Ann Darrow to the top of the Empire State Building, he places her on the ledge near the fixed ladder mounted to the building. During the scene, in Ann's close-ups, the ladder vanishes from where it should be, and in the zoom-in shots (biplane POV), the ladder is mounted in a different area than in the long shots. (01:35:00)
Revealing mistake: While King Kong is atop the Empire State Building, the biplanes are strafing their large target. There are several static close-up shots facing a biplane's nose, and in these "aerial" shots, there's a girder beneath the set prop's fuselage. (01:36:10)
Revealing mistake: When the sea creature appears and the raft overturns, the people falling are very obvious stiff dummies. One even falls downwards and its two feet stick up from the water.
Continuity mistake: When Denham shows a second map to the captain, one can see it has a big map on the center part. In the close-up, it swaps to being a small drawing on a side.
Continuity mistake: In New York, Kong fetches a woman in her sleep. In the close-ups she's wearing white pyjamas, but the mannequin she's replaced for when she falls has short hair and dark clothes.
Continuity mistake: When Kong lifts Ann from the bed she is wearing a short dress. In the close-up the dress goes way down to her ankles.
Trivia: For a single frame, one can see the structure that holds the Kong puppet. The first time it's still visible in modern copies at time code 00:52:36 (after the people run away on a log used as a bridge). The second one was digitally removed years ago, and it takes place when Kong exits the cave right after Ann faints. (00:52:36 - 01:05:30)
Continuity mistake: Kong keeps changing styles throughout the movie at least 4 times: In the close-ups of its head it either has a round face with dirty teeth, fangs and small nostrils or white teeth with no fangs; as opposed to the full body models where it swaps between a cone-head forehead with small nostrils, and a rounder one with larger nostrils, both models with pearly white teeth.
Continuity mistake: The right cuff of Kong's shackles disappears from his wrist when he destroys the train, only to reappear later on.
Continuity mistake: The planes that attack Kong have two parallel wings, the lower wing being shorter. In the close-up of the planes next to Kong both wings are the same size.
Continuity mistake: Kong shakes the sailors off the log and a man falls down. A shot later he's back on the log. (00:53:12)
Continuity mistake: During the fight between Kong and the dinosaur, the shape of the tree Ann is on differs between shots.
Continuity mistake: After Kong escapes from the theater, a car crashes against a wall with no glass on the windshield. In the next shot, broken glass appears.
Revealing mistake: At the Empire State, the woman is an obvious square-shaped footage of film pasted on top of the footage of Kong. After the plane attacks Kong and his right arm goes limb it goes behind the pasted footage.
Answer: It's never shown or explained, and the film uses a broad "suspension of disbelief" premise. The audience just accepts the characters were able to somehow transport a huge ape to New York City.
raywest ★