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.
Revealing mistake: When Herod shoots Rusty in the back before the final gunfight, a car can be seen driving down the road in the background.
Revealing mistake: In the scene at the end of the movie where Lee Marvin is running interference during the escape by shooting in the air, horses pulling a beer wagon get startled and run into the street where the wagon turns over. At the beginning of the shot, when the horses begin to bolt, you can see the stuntman driving the wagon. He is sitting low behind the wooden front of the wagon (which has holes cut in it so he can see out).
Revealing mistake: When The Deputy Charley Rakes goes to Cricket's house and attacks Jack, you see Charley throw Jack down the steps outside the house. If you look closely, you can see he lands on something really soft and spongy like a mattress which is hidden under the foliage on the ground to break his fall. When Charley walks down the steps towards Jack, you see him walk on it, which again looks really soft and spongy.
Revealing mistake: In the scene where the boy is shot in the leg and the carried away by an unionist soldier you can see more union soldiers storm past them. The bayonets of the soldiers are obviously made of rubber as they are dangling while the rifles are moved up and down by the running soldiers.
Revealing mistake: After the trailer explodes on the bridge, towards the end the truck swerves to the left. As it drives off the bridge there is no tail shaft between the gearbox and front diff - the truck falling off the bridge is just a shell.
Revealing mistake: The caboose and two bunk cars are uncoupled and sent rolling down the hill, with troops locked inside. As the cars roll off a cliff, troops can be heard yelling. However, as the cars hit the ground and shatter into rubble, the wood does not appear to be blood stained, nor does there appear to be any sign of bodies in the debris. The cars were obviously empty for the scene, and given the circumstances of the soldiers allegedly trapped within them, it's unlikely that any of the soldiers could've gotten out in time.
Revealing mistake: When we see a wagon with a woman and several children in it, the horses get spooked and run. A woman is seen desperately trying to stop the runaway horses. In the next scene you can see the children are not real and the woman is a man dressed in a woman's dress, obviously a stunt man used for that scene.
Revealing mistake: In the Gatling Gun scene when the camera cuts to a short couple frame shot showing a closeup on the .45-70 Government ammunition casings on the ground that are falling from the gun, the casings are star crimped. Star crimped casings indicate blank ammunition. Standard ammunition isn't possible with star crimping. The size and casing shape indicates .45-70 Gov which was popular in these guns at this time. (01:46:40)
Revealing mistake: During "Many a New Day", when Laurie sings "many a red sun will set" and before they all hear the Cummings girl laugh outside, Laurie and two others are looking into a mirror. The actresses are actually looking into the camera through a mirror frame, to give the illusion that we are seeing their reflections. When the girl with the long black hair joins them, you see her run in from the side, then her "reflection" in the mirror. However, if it was a real mirror, you wouldn't see her run in from the side. (00:44:00)
Revealing mistake: Near the end of the movie, the Bunch are relaxing and passing around a bottle of whiskey. While the actors could not be expected to drink real alcohol, it's too bad the prop guy could not have mixed up some less foamy instant tea, typically used as a substitute in these scenes.
Revealing mistake: During the bison shooting scene, a bison goes down close to the camera and both horns jiggle like they're about to fall off. Looks quite fake. (01:00:06)
Revealing mistake: When Cactus is ran over by the train, one can see he is held with several security straps.
Revealing mistake: When Jordan and Jett go into the liquor storage room for Jordan to teach Jett a lesson for beating up Jordie, Jordan instead throws a large wine basket at the shelves of wine/alcohol. The shelves start to fall before the basket even hits them. (02:44:55)
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: When Caleb shows Mae his horse and it rears you can see the man holding the horse's rope is not Caleb. The man has an older, redder face and greyed sideburns. (00:08:21)
Revealing mistake: The gang's visit to Northfield, Minnesota reveals a typical late 18th century town, with dozens of people on many horses and horse drawn wagons. All the horses leave deep tracks in the dirt, because they are walking on freshly laid soil that has not had time to compact. There is absolutely no horse manure to be seen anywhere, despite dozens of horses. Clearly, the film makers used a 20th century town and laid new soil over the pavement shortly before the filming began.
Revealing mistake: In the scene when Crow Horse and Levoi are running from Coutelle and the "GOONS", they go off-road toward the stronghold. You can see in the grass the tire tracks from all the other takes. Especially as there is no reason any vehicle would leave the road at that place otherwise.
Revealing mistake: When Ransom and Hallie Stoddard are riding the train back to Washington at the end of the film, pay attention to the view out the window as Hallie responds to Ransom's suggestion of returning to Shinbone. When the conductor brings the spittoon and talks to them, the same exterior footage repeats from when Hallie started to speak. (02:01:30 - 02:02:15)
Revealing mistake: Many of the cavalry soldiers were carrying M-1 Garand rifles (WW2 era rifles).