Revealing mistake: During the sequence with the Native Americans chasing the Delorean in the beginning, in one shot looking up at the sky you can see contrails from a plane, obviously not around in 1885. (00:19:25)
Continuity mistake: As Mr. Fletcher is riding up on horseback to greet Lady Ashley, you can see him riding up next to a parked, red truck, that has the front end pointed away from the house. Keep an eye on that truck, because it will have the front end pointing towards the house, as Fletcher gets closer to Lady Ashley. (00:27:50)
Continuity mistake: In Kate's hotel room, when she's trying to get away from GW she steps backwards through the hotel room's doorway onto the porch, and falls straight through the broken wood railing, but when GW looks down at Kate on the pile of hay, there's now a window behind GW, not a doorway, and clapboard siding has suddenly appeared on the hotel wall as well.
Factual error: There appears to be a pickup truck parked by a barn in the background when Steve McQueen is standing by his horse, talking to Linda Evans. (00:19:00 - 00:20:00)
Visible crew/equipment: As Ennis leaves for his first fishing trip with Jack, Alma is holding Alma Jr, whose pajama shirt is lifted. Alma Jr's microphone wire is visible on her stomach. (01:08:45)
Continuity mistake: Near the end when they're entering the Mexican village, Billy's coat disappears as he rides through the gate. (01:17:45)
Continuity mistake: When Blondie abandons Tuco in the desert, watch the rope around Tuco's neck. It changes between shots, sometimes over his left shoulder, and sometimes hanging down in front of him. It is not due to the camera angle.
Revealing mistake: When the stagecoach driver gets hit with an arrow, it springs up from below into a horizontal position. (00:33:55)
Continuity mistake: At the start, the kid drops his popcorn and we see a shot of it right next to his foot. A couple of shots then follow but he's always visible, not moving. We then see a wide shot and he's further from the popcorn.
Continuity mistake: During the ambush on the river two Indian braves can be seen firing arrows one gets shot and dies but the brave who is left his hair and clothing are wet. The scene cuts away and when it cuts back to this brave he stands up only to get shot in the heart. He clutches his heart with both hands and then dies by falling into the river but now his clothes and hair are completely dry. It's clear that the earlier part was a retake after he fell in the river.
Visible crew/equipment: During the attack on the town, right after Jake breaks Percy's hand to get out of the cuffs and begins kicking the wagon door we see an exterior shot of two people running and just before one does a flip, film crew is visible on the left. We see at least two people sitting in chairs, one wearing a bluish short sleeve shirt, shorts, and boots, and another in a white shirt wearing a baseball style cap. We also see a blue light coming off their equipment. (00:35:30)
Visible crew/equipment: The first time we see Fogg the shadow of the camera operator (film director?) and camera sliding smoothly along tracks is perfectly visible.
Revealing mistake: When Potter starts shaving at the morning of the Indian attack on the wagon train, his mirror falls off the post, and as he bends down to retrieve it, an arrow embeds itself right above his head. If you look closely in that scene, you can see a length of targeting wire used to guide the arrow sticking to the post above Potter's head. (00:37:10)
Revealing mistake: During the shooting in Candieland, right before Django bursts a man's head, a man next to Django who he uses as a shield has his chest burst. The blood pack is very noticeable.
Continuity mistake: When Hiram, Juan and Kelly first see Old Fred's wagon in the distance, the white tarp on it is draped across it and down one side. When they arrive at it, it's draped differently. They also arrive at it from the side, when they were approaching from straight in front on it. (00:46:15)
Continuity mistake: Otter Bob holds out a bottle of liquor at Isaiah after he kills a bear. In the close-up, Bob is holding the bottle by the neck. In the wide shot, he's holding it by the body.
Continuity mistake: Juliano and Joaquin are having their pictures taking celebrating the first earnings from their own gold pit. All of a sudden between shots, the photographer loses the cigarette behind his ear. (00:18:50)
Continuity mistake: David Hackett is talking business organizing ranch business while his brother Ed is leaning on the counter, gawking at the beautiful Clee and passing her cloth. He has his right arm up in the close-ups, but the left arm up in the wider shots. (00:04:55)
Continuity mistake: At the beginning, Belle dismounts from the horse and gets in front of Mammy Lou. Her hands are lowered in the wide angle but raised in the closer view. (00:04:00)
Continuity mistake: When Waco Kid is lying down on hay bales at the end of the film, there is no horse. All of a sudden when he's invited somewhere by Sheriff Bart, a horse appears. (01:33:50)
Suggested correction: It is true that the horse suddenly appears, but Jim is reclined on hay bales, not boxes.
For future reference, this is what the "change the entry's wording" option is for.
This entry is about the sudden appearance of a horse. It has nothing to do with The Waco Kid reclining on boxes nor does the entry say he was reclining on boxes. It says that he's reclining on bales of hay.
It did say bales of hay - I've left the correction and "change wording" comment online for a bit for informational purposes.