Continuity mistake: When Ann meets Kong on NYC street, the camera flashes back and forth between them. When it shows Kong, he is surrounded by snow, but when it shows Ann, the street doesn't have so much as a snowflake.
Other mistake: When Ann Darrow is awaiting sacrifice to Kong she is hanging from tight thick ropes around her wrists. However, when Kong shows up he just grabs her and tears her from the plinth. Either the ropes should still be around her arms having been torn from their mounts, or her arms should have been ripped off.
Continuity mistake: When Anne comes out of the lake after fighting with the T-Rexes her hair is all wet, but after Kong has defeated the last Rex and puts her on his shoulder to start running, her hair is totally dry. Same happens after she and Jack crash in the river after letting go of the bat. Next shot you see them running towards the temple and her hair is, once again, completely dry.
Visible crew/equipment: On Skull Island, when Carl says, "No one has lived here for hundreds of years," the distinctive reflection of the reflector screen is visible in the lens of Preston's glasses, as he looks down; there are other moments in the film where this happens with characters' eyeglasses.
Continuity mistake: When Bruce Baxter tries to wiggle his way out of having to get closer to the brontos so Carl Denham can get his scene on film ("Shouldn't there be a stand-in for this?"), the gun he holds that can be seen pointing up over his left shoulder keeps appearing and disappearing between shots from the front and back.
Revealing mistake: Near the end of the film, when people are running in terror out of the theater and into Times Square, you can see that the people are not leaving any footprints in the snow. The snow must have been digitally added to the scene.
Continuity mistake: In the scene where Ann Darrow is brought to the Venture, there is a wide shot where she is walking and observing the ship. On one of the ramps (the closer one to her), there is a man who is carrying something up the ramp. In the next shot, if you look at the ramp he was on, he has disappeared.
Revealing mistake: When Ann is juggling for Kong on the cliff edge she starts juggling at one point. If you look closely, you can see that she is simply moving her hands, and the rocks have been added digitally. This is most obvious when she leans right back, and the rocks don't match her hand movements at all.
Continuity mistake: Note the chrome centers on the wire wheels of the taxi that Jack commandeers towards the end of the film. Initially the left rear one is missing, but it magically reappears later on.
Continuity mistake: Soon after Kong grabs Ann for the first time and is playing with her the wide shots show him violently shaking her around, enough to snap her neck or at least render her unconscious, but the close-up shots during the shaking show her being much more gently rocked from side to side.
Continuity mistake: As Jack Driscoll flees Kong in a yellow cab through a narrow alley, the view through the (missing) windshield shows a pedestrian in light-color overcoat crossing leisurely at the other end. When the car eventually emerges in the immediate next shot viewed from the sidewalk, that particular pedestrian simply disappears.
Factual error: In at least one shot as Kong is on top of the Empire State building, the sunrise over Long Island is wrong. Three planes attack from the southwest and we see the sun rise in the east as Newtown Creek (Nassau River) glistens across the East River. The mouth of this river opens southward but in this shot everything is inverted with the mouth of the river pointing northward. Also, looking eastward, Roosevelt Island should be on the left of Newtown Creek, not on the right.
Continuity mistake: At the end of the chase through the streets of NYC, Kong stops the yellow cab with a "karate chop" to the front-end, which sends the car tumbling high into the air through a complete somersault before it lands back down. Actually, Kong's hand is still half way down and nowhere near touching any portion of the vehicle when its rear-end gets lifted.
Continuity mistake: When Jack is rescuing Ann she has two cuts above her right eyebrow, the smaller cut changes positions and disappears/reappears in different shots.
Factual error: In the scene where Kong is running around the streets of New York City and being chased by two military vehicles, the lead open-topped sedan has an air-cooled 30 caliber machine gun mounted on a bar behind the driver, with the gunner in the back seat. The time setting of the movie is 1933-1934. Air-cooled ground mounted machine guns were not in general use until 1942, and were not available for aircraft until 1936. The Army used water-cooled machine guns until the start of World War II.
Continuity mistake: When Carl falls at the beginning of the brontosaurs chase we see that he is only just in front of the brontosaurs so when he fell he should have been crushed straight away but he isn't. Jack then runs to help him and we see that the brontosaurs only need another step or 2 (which would take 1 or 2 seconds) before they reach Carl and Jack. Carl gets up and argues with Jack for 5 seconds or so by which time they should have been crushed. They then run and there is a far off shot showing the brontosaurs back where they were at the start again.
Continuity mistake: Just before the wall is spotted, Jimmy is in the open crow's nest reading "Heart of Darkness". He puts the book down and stands up. In the next few shots, the book has completely disappeared. Then the ship takes a pounding for 3 or 4 minutes. But a few minutes later there's Jimmy, once again reading the same book.
Factual error: The drop fare on the taxi is shown as 25 cents. However, this fare was not charged until 1952, when the former taxi fare of 20c 1st 1/4 of a mile and 5c each additional 1/4 of a mile (which went into effect in 1934) was increased to 25c the 1st 1/5 of a mile and 5c each additional 1/5.
Continuity mistake: When Kong falls through a portion of the circular observation deck at the top of the skyscraper, he crushes the metal siding as well as one of the metal girders, making a large hole. When he puts Ann inside through the hole, the metal girders are now all undamaged. You can tell that this is the same hole because the camera moves around the entire building in the next shot and there are no other large holes.
Revealing mistake: When Carl is standing next to Kong's unconscious body saying, "His name will be in lights on Broadway," look at the Venture in the background. Even though it's not stuck on anything, and despite the choppy waves, it doesn't move ANY. Even if anchored, it would still bob gently in the waves; instead it's frozen solid. Obviously green-screened, or possibly a matte painting.
Audio problem: After the scene where the men had to fight off the giant bugs, there is a wide shot where the men can be seen being helped out of the pit by the captain and a few extra crewmembers. The captain is shouting something, however, if you look closely, his mouth is not in sync with what he is saying.
Continuity mistake: Shortly after Kong realizes he's been shot and gets blood on his fingers by touching the bloody hole in his chest, in subsequent scenes his chest has no puckered indentation and is unblemished but for minimal straight-line scars.
Continuity mistake: On the cliff where Ann is entertaining King Kong by dancing, juggling, doing flips, etc. her face goes from dirty, to clean, to dirty, and back to clean between shots.
Continuity mistake: Ann is soaking wet when she is being led through the natives. When she gets to the top of the wall she's dry.
Factual error: In the scene where Denham is getting a wide-shot of the valley where they first spot the dinosaurs, Denham's assistant is using a light meter in a brown leather case. This light meter is unmistakably the 'Weston Master Universal model 715/S74'. This model was first produced in 1939. Since the film takes place in 1933-34, this model of light meter would not have existed.
Continuity mistake: When Carl is convincing Ann inside the diner, after she stands up and Carl convinces her to accept the role, there's a waitress behind Carl about to walk towards her. A split second later, while Carl says "she's the saddest girl he's ever met", the waitress appears 12 feet away, and is now behind Ann way at the end of the diner.
Audio problem: When Carl tells Preston to show Ann on board the ship he says something like, "Hello, Miss Darrow, I'm Mr. Denham's assistant." His lips aren't properly synchronized with the dialogue when he says this.
Continuity mistake: When Kong is about to fight the last Rex, Ann begins to back under his arms. In a distance shot we see that she is already a fair distance behind his arms, underneath him. Cut to Kong noticing this, then cut back to a back shot of Ann backing under and she has not even reached his arms yet.
Revealing mistake: Despite being thrown, falling, being dragged and various other things, Ann's hair and face are almost always clean. Even when there does appear to be some dirt, in the next shot they are clean again.
Continuity mistake: Kong continues to change size during the movie. The most obvious way to notice this is when his hands are near Ann. When Kong first finds Ann in NY, his hands are 3/4 the size they are immediately after when he picks her up.
Factual error: When Denham sees the smashed camera he sees the film stock spilled on the ground. It is brown, indicating unexposed colour stock. Brown emulsion film didn't exist in those days - it was introduced by Kodak in 1943. In those days it would have been black and white emulsion, blue on one side, and grey on the other. Colour films in the early 30s were made by painting black and white films frame by frame or printing the monochrome negative three times and staining each one a different primary colour.