Continuity mistake: In the early-morning scene at Mr. Brownlow's house, Oliver is shown sleeping in his bed. He awakens and his hair is in complete disarray as he walks towards the open balcony doors. Standing on the balcony and gazing outside, however, his hair is combed neatly.
Revealing mistake: Most of the posed, fake displays in the ape's Museum of Natural History contain real people who are slightly moving if one pays careful attention. Especially noticeable are those posing with objects held in - or above - their hands.
Factual error: The final scene of the movie has Col. Kirby and the little Vietnamese boy supposedly on the beach at Da Nang, Vietnam. Kirby is saying, "The future of 'nam is you, kid", and the camera pans out to the sea and the sun is going down. The sun's sinking in the east...
Suggested correction: Nowhere in the film are we told where in Vietnam the Green Beret base is, just that it is in South Vietnam (of course). South Vietnam has a Western coast, along the Gulf of Thailand, along which anyone can watch the sun set over the sea.
Around the 18:00 - 18:30 mark a character welcomes John Wayne to Da Nang. This base is returned to throughout the film, including the infamous sun setting in the east scene. Da Nang's beaches face to the Northeast. Only when you get south of Nha Trang does the Vietnamese coast begin to offer a south to southwest horizon on the ocean.
Continuity mistake: At the beginning, Eastwood dismounts from his horse to rescue the calf lying in the river. His horse is left standing in the river with the water up to his knees. When Eastwood places the calf on dry land, his horse is standing nearby. The horse's legs are dry.
Continuity mistake: When the team are about to jump from the cable car into the river, the view from ground level shows a bare road with no snow on it on the right and a line of trees on the left with German trucks parked next to them, but the view from the cable car shows a snow-covered road and no trucks beside the trees. (02:06:00)
Continuity mistake: Steve McQueen passes the same green Volkswagen at least three times while chasing the black Dodge Charger R/T. This is due to the same downhill portion being shown to us from multiple angles to artificially extend the length of the scene.
Revealing mistake: When you see the first shot of the dead Mercutio, he's still breathing.
Continuity mistake: Minnie gives her the necklace with the tannis root inside and Rosemary holds the chain between her thumb and first two fingers. In the next shot the chain is draped over her fingers. (00:32:15)
Character mistake: The crew many times refers to the sub as a ship - subs are always called a boat.
Continuity mistake: At the very end Fleming sees the dead body of his girlfriend being hoisted onto a gurney - she is soaking wet, having been hauled out of the swimming pool. Later we see it is a policewoman acting as a stand-in in order to fool him into talking - and after a few minutes under a blanket on the gurney she, her bikini, and her hair are all bone dry. Not only that, her hair looks like it has just been styled and her makeup is perfect.
Other mistake: In the opening credits, the copyright year is shown as MCMXLVII (Roman numerals for 1947), when it should be MCMLXVII (1967).
Continuity mistake: At the end of the movie when Cheyenne is shaving, while Harmonica and Frank are having their shoot-out, he cuts himself at the sound of the gunshots. When Jill tells him that he is a handsome man the cut is gone. (02:22:25)
Continuity mistake: When doctor Nemur, that other doctor, and Mrs. Kinnian are discussing possible complications with Charlie's surgery, there's one shot where Dr. Nemur takes the cigarette out of his mouth and in the next shot it's back in.
Continuity mistake: In the last scene of the movie Eleanor leaves by boat to go back to her castle prison. When we see Henry waving good-bye he is standing right next to a post when we see him from the back, but this post is nowhere when he is shown from the water. (02:08:10)
Continuity mistake: When Coogan first meets Julie in the New York police station and puts her coat on for her you can see his cigarette in his hand, then his mouth, then his hand again as the camera angle changes.
Revealing mistake: During the bank hold-up at the beginning of the film, one of the pushes a man on the wall. It wobbles like cardboard.
Factual error: The German tanks are American M47s, post WW2. They had the same hulls as the M46s (also post-WW2), but a better slope and greater effective armor on the turrets.
Factual error: In the famous tugboat scene, Fannie rides out on a New York Central tugboat painted jade green - a color which wasn't instituted on the boats until the early 1960s. To be accurate, the tugboat would have to have been painted red with a black stack and the New York Central logo.
Continuity mistake: Many times, especially in the second half of the movie, the background color changes between shots even in two shots of the same set.
Revealing mistake: When Buck and the gang ride away from the saloon in Dallas where JC made a few new 'friends', the footage is sped-up for a second just as soon as James Caan jumps on his horse. (00:05:50)