Factual error: In the final scene, where Fonda and Holbrook are looking over the carrier at the crowds on the dock, you can see that only the first rows of people are dressed in period clothes. The rest of the crowd are dressed as they would have been in 1976 when the film was made. Also, between them in the background is a yellow Ford Pinto.
Visible crew/equipment: During the final fight, a steady cam operator with a white shirt and black straps around his body is seen during several wide angles. This is not a TV camera, it is a film crewmember. The Director even admits to it in the audio commentary on the DVD.
Deliberate mistake: The rail line was supposedly not used in 30 to 40 years, however, in the exterior scenes approaching the bridge where the mile markers were, the tracks are well maintained, has no vegetation, and the rails are shiny, indicating a lot of train use.
Visible crew/equipment: In the scene where Laura is being attacked in the desert, the camera swings wildly. During this swing, the entire crew becomes visable for a split second. You can see Clint Eastwood (who also starred in the film) sitting in his director's chair, wearing a white t-shirt and watching the filming closely. (01:19:54)
Factual error: The fact that the respiration of a single animal - however large - could lead to an increase in the level of carbon dioxide in the local area is so absurd it is laughable. Carbon dioxide exhalation is part of a closed loop cycle and the CO2 exhaled by Kong would be matched by the CO2 taken in by the plants growing on the island. It cannot be otherwise. Elevated levels of carbon dioxide are incredibly dangerous and any animal living on the island - including Kong - would suffer if things got out of kilter.
Visible crew/equipment: When the train cars are decoupled, behind the vapor cloud, a person is hanging from the left side of the train car but does not resemble any of the characters in the scene. (01:47:00)
Continuity mistake: In the scene where Cannonball is driving the Mustang and Redman is driving the Charger through the incomplete Interstate, they begin bashing each others' cars to bits. Several shots show the badly damaged cars and the results of the multiple hits taken. However, when we are shown the cars just before the bridge jump sequence, neither car appears damaged.
Other mistake: Although the Lieutenant is actually sent to the police station in precinct 9, division 13, the sign over the door states it to be division 14.
Continuity mistake: When the soldier demonstrates the bazooka on a truck, the projectile hits the front of the truck, but the explosion comes from near the back of the truck.
Factual error: At the start of the movie, the nuclear-powered articulated bus that is attempting a non-stop land run to Denver leaves New York City, but you can see the Rocky Mountains in the background.
Continuity mistake: When Christella is slapped by the possessed Ike, her pose changes between shots.
Factual error: When a Rear Admiral and Captain are walking together, the Captain's epaulets are the wrong way round. A cardinal sin in the Navy. (01:30:00)
Revealing mistake: By order of the shrewd Harry Webb, the helicopter just destroyed the Cessna on the ground. The two guys decide that they are gonna walk back to civilization. Cut to the vehicle driving to the explosion site, and you can see in the desert sand ahead of the jeep fresh tire tracks from previous takes. And it keeps happening during the desert chase. (00:10:20)
Continuity mistake: The movie opens with a gang of thieves taking the luggage of several Japanese tourists distracted by a guy pretending to defecate on the lawn. One of the robbers is snatching a bright red suitcase in the first shot, which turns into a plain brown suitcase in the next. Also in this second shot one of the bags is lying on the street, while in the previous they were all on the sidewalk. (00:02:40)