As Calvin Candie rides in the carriage towards his house the smoke from his cigarette blows away to his right. When the carriage then parks up for him to introduce Schultz and Django to Stephen the smoke is blowing across in front of the house, i.e. in the opposite direction.
Stephen (Samuel L. Jackson) uses the word "motherfucker" four times throughout the film. This is a linguistic anachronism as the word didn't exist until the WWI era (the Oxford English dictionary lists the earliest use in 1918).
Calvin Candie compares a slave to a teddy bear, even though teddy bears were not invented until the time when Theodore Roosevelt was president, hence the name "teddy". Oddly enough, the film is set in 1858, that president's birth year.
The movie depicts the characters having and using guns that employ metal cartridges. Those would not be available in 1858, the standard round at the time being a paper cartridge containing powder and ball and a separate percussion cap.
The film mentions Lubbock, Texas. Lubbock did not exist in 1858 and would not come into being until well after the Civil War (Lubbock was founded in 1876 and the film is based in 1858 and proceeds through the winter into the spring of 1859). In 1858 the Panhandle of Texas was not traversed by the faint-hearted as it was essentially populated by only Kiowas and Comanches.
Calvin Candie is seen smoking a cigarette with a cigarette holder in several scenes. The year is 1858. The cigarette was not mass manufactured in the USA until 1881 and the cigarette holder did not become popular until 1910.
During an auction, Dr. Schultz calls out, "Sold, American!" But this line wasn't made famous until the 1920s when fast-talking auctioneer 'Speed' Riggs said it at the conclusion of Lucky Strike radio commercials. Also, "American" is in reference to the American Tobacco Company, which wasn't in existence until at least 20 years after the time the film is set in.
Several characters pronounce the word "valet" to rhyme with "ballet." This mispronunciation did not gain popularity in the United States until after 1950. Before then, it was pronounced to rhyme with "mallet."
Calvin Candie drinks a tropical drink through a straw. Straws were not sold commercially until 1888, although hollow reeds were used as straws before then. However, the straw in the film does not appear to be a reed.
At the Cleopatra club, the winning fighter receives a typical bottle of beer, similar to the Dutch Grolsch bottles, however, this type of bottle was not patented until 1875 by Charles de Quillfeldt, 16 years after the time the movie is set in.
After Django and Dr Schultz have ambushed the cowboys, Dr Schultz is seen removing a bullet shell from the rim of his hat and drops the shell on the ground. A metallic 'ping' sound is heard when it falls on the ground off screen. But as they are standing in the snow, the sound of the shell falling on the ground would normally not be heard.
When Butch pulls a shotgun on Django and Dr. Schultz at Calvin's dinner table, he pulls out his revolver to point at the Doctor. Yet in the next cut he is pointing only the shotgun at Django, then the next cut he is again holding both weapons.
When Django and Dr. King Schultz ride in to Candyland for the first time the fields in front of the gates are harvested/cut. When Django and Broomhilda leave Candyland together the fields have tall grass.
Before Django, Calvin, and Dr Schulze arrive at the plantation, Stephen fills out a check to The Harris Feed Co. for "Sixty Five Dollars", but the numbered amount is for $68.00. After Stephen stamps the check, the camera zooms on the check revealing a different check for the right number amount of $65.00.
When the group first arrives in front of the house at Candyland, Stephen comes out to speak with Calvin Candie. When shot from behind, Candie is sitting in the carriage with his legs crossed, and when the camera angle switches to the front, his legs are uncrossed. This jumps back and forth a few times.
When Django is learning he is allowed to dress himself as he pleases, as he tosses the hat onto the bust in frustration, it rests off-center and pointing to the floor. But when the camera cuts back, the hat is suddenly level.
After the foyer shootout at Candyland when Django is seen hiding underneath the knocked-over cabinet about to surrender, a body is shown lying on its back directly in the middle of the hallway. Moments later as the camera pans over the array of bodies from the shootout, the body is moved to the left side of the hallway closer to the wall.
As Shultz and Django ride up to the mansion the first time, the sun appears to be setting (or rising) from the left. As the scene progresses, the sun shifts sides, throwing the shadows of the shrubs and actors in opposite directions. This continues through the scene; sun from the left, sun from above, sun from the right, overcast.
When Big Daddy turns up after Django and Schultz shoot the Brittle brothers, his hair is damp under his hat, when the camera jumps back to him it's back to being dry, it changes back and forth with each different camera cut.
When Dr. King Schultz is speaking with the four remaining slaves (after freeing Django), he is holding the reins of his carriage with his right hand and is gesturing with his left hand. When the camera angle changes mid-sentence, he is holding the reins with his left hand and his right hand is suddenly raised.
While Schultz was talking to Big Daddy on his cart, right after he introduced his horse, Fritz, we can see 6 people walking toward them near the gate. When the scene cuts to focus on Django, only 3 people are shown where there were 6. Then when it switches back to both Django and Schultz, there are again 6 people there.
On the way to CandyLand, Django pulls one of the henchman's horses to the ground, bringing the rider with it. In the next shot, the rider is still on the ground, but the horse is suddenly upright as though nothing happened.
When Dr. Schultz and Django are riding into Daughtrey, they encounter a young goat herder with a herding staff in his left hand and a leashed goat in his right. In the next shot, the staff is in his right hand, and the goat in his left.
When Dr. Schultz is casually mentioning to Hildy that there is a "friend" on the other side of the door behind her, many reflections of activity by the crew and camera are seen reflected in the glossy bedpost behind Schultz, as he sits in his chair. Neither character, in this scene, is moving.
In the film there is a cotton plantation located in Gatlinburg, Tennessee. This region (The Grand Division of East Tennessee) is very mountainous and inhospitable for cotton, preventing large plantations from arising. As a result, the region had a low slave population which translated to anti-slavery and pro-Union sentiments in the years leading to the Civil War.
The profile on the door sign to the Cleopatra club and the bust in the entry hall is not Cleopatra but in fact Nefertiti. Also the bust and related profile wouldn't have been known in the 1850 due to the fact that the bust wasn't discovered until 1912.
During the opening credits, the Speck Brothers have Django and five other slaves in chains. When Dr. Schultz catches up to them after the credits, there are only four other slaves. However, this is because the slave march depicted in the opening credits takes place over a week or more. At least one of the actors is different, because slaves were swapped out along the march, possibly including death. It has been stated in interview that this was deliberate, to depict the way a slave march would actually be.
The men in hoods pursuing Dr. Shultz and Django are often mistaken for the KKK, which wasn't founded until 7 years after the events of this movie, in 1865. However, according to Quentin Tarantino the men are predecessors to the Ku Klux Klan called the Regulators.
After Candie is shot by Dr. Schultz, the camera zooms in on Stephen as he screams. For a brief moment, Butch is looking over his shoulder at Candie after he falls to the ground, all while pointing his gun at Broomhilda. However, once Stephen begins walking over towards Candie, it is shown that Butch is still facing Broomhilda and had not turned around yet. The camera then zooms in on Butch as he looks over his shoulder to see what happened.