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)
Other mistake: In the Todd-OA version, just before the song "Oklahoma." Gordon MacCrae puts his hand on the porch post and the post moves off the rail. He then pulls it back.
Factual error: Approximately 2 hours and 10 minutes into the "restored" full-length video version, there's a birthday party for little Lisa Dickinson, and the Alamo defenders sing "Happy Birthday" to her. The Alamo battle happened in 1836. According to David Ewen's "All the Years of American Popular Music," the song "Happy Birthday to You" was composed and copyrighted by sisters Patty and Mildred J. Hill, first as "Good Morning to All," in 1893.
Continuity mistake: At the end the nasty man is out of bullets so the Bad girl throws him a bullet from her rifle. He puts the bullet in but fails to revolve the cylinder so of course he loses as you would have to thumb-cock and pull the trigger 3-4 times to get to the live ammo. Dumb, dead desperado.
Revealing mistake: In the final scene as Doc tell Billy good-bye if you look up to the top right hand corner of the screen you can clearly see a jet trail in the blue sky. Certainly not possible in those days. (01:42:20)
Continuity mistake: At the fair when Isabelle goes to give Suzanna the baby, she actually hands it to her in one shot, but in the next (a split second) Suzanne shows no sign as if the baby ever left Isabelle's hand. (01:38:24)
Continuity mistake: In the barn dance scene Gideon is doing flips on the sawhorse. His shirt becomes untucked and then retucked between flips.
Continuity mistake: When Rick Nelson tells Angie Dickinson to throw the plant pot through the window to distract the gunmen who threaten John Wayne he seems to have had a hair cut between scenes as his sideburns are halved by the time he reaches the street and grow again later.
Continuity mistake: There is no way the cow (a Hereford I think) could have given birth to that calf (a Jersey or something like that). [The mom is a mixed-breed BEEF cow, the calf a purebred Jersey DAIRY calf. An amazing feat of animal husbandry.]
Revealing mistake: When McKay and Ramon are riding into Blanco Canyon to rescue Julie, you can see a diesel loading shovel with its bucket raised in the bottom of the frame of one of the scenic shots. Presumably the scene was shot in a quarry and they didn't get all the equipment out.
Factual error: When Bob Ford opens the box under the bed, on top is an issue of "The Jesse James Stories" weekly, which was published from 1901-1903 - fully twenty years after the events of this film. (00:36:10)
Visible crew/equipment: At Lees Ferry when the stagecoach is crossing the river, there is a shot from on top of the stagecoach. As the camera pans over to the river, a clear shadow of the camera and its film magazine are visible.
Continuity mistake: When Jack Twist is chopping wood, right before Joe Aguirre visits him on his horse, he sets up a piece of wood to chop. Jack talks to Joe and when the camera pans out to show him ready to chop again, the piece of wood is gone.
Revealing mistake: In the scene out West with the buffalo, notice the car driving in the distant background.
Plot hole: Towards the end of the film when Newman and the remaining stagecoach people are in the cabin at the top of the hill, Richard Boone's character sends one of his two henchman (the Anglo, not the Mexican) around to the back of the cabin to apparently surprise them from behind. Then Newman's character walks down the hill and Boone and the Mexican henchman are all killed in a shootout. Everyone comes out of the cabin, comes down the hill and the credits roll. I guess that now, almost 40 years later, that poor Anglo-henchman is still behind the cabin, waiting for them to come out.
Revealing mistake: As Jango fires the machine gun, the ammunition chain hanging from it is loaded on both sides, and it doesn't move. Also the belt has different sizes of cartridges in it. (00:45:30)
Other mistake: Bandoleer rounds don't fit any weapon in the show. When Pierce tries the Gatling gun, there is no magazine in it.
Continuity mistake: At the start of the train chase Tonto blows the whistle as he passes the bad guy who says "shoot him you idiot". The soldier opens fire with the machine gun and Tonto is suddenly back in front and passing him again. (02:03:35)
Character mistake: When Vallian prepares to leave the homestead, McKaskell asks him how his chest wound was. Vallian was shot low on the right side, just above the gun-belt, and McKaskell, who removed the bullet, was quite aware of the location.
Continuity mistake: When the church bell is rehung and struck, it goes from shoulder height to well above head height, then back to shoulder height in subsequent shots. (01:28:15)