Factual error: Throughout the film, Dr. Schulz and Django use what appear to be a Remington Double Derringer. The double barreled Derringer wasn't introduced until 1866.
Factual error: When Django blows up Candyland at the end with a bundle of perhaps 30 or 40 sticks or so of dynamite, he casually moseys out the door, and turns around and watches from maybe 100 feet away. With an explosion like that, completely obliterating an entire mansion, from that distance, the shock wave would have sent him flying and probably killed him. He was far too close to be safe and emerge unscathed from the explosion.
Continuity mistake: In the opening scene where Schultz and the Speck brothers first meet, Schultz gets off his carriage and lights a lantern. However, the already lit lantern hanging from the left side of the carriage goes from lit, to unlit (or missing), and back to lit as the scene progresses. (00:05:00)
Factual error: When Django and Schulz ambush a group, they kill them with their Henry repeating rifles. That rifle was introduced 2 years later, in 1860.
Factual error: Django carries a Remington "New Model Army" revolver, as does Billy Crash, shown when he holds it to Hildi's temple. These weapons, although based on an 1858 patent, were not produced until 1860.
Factual error: At the end of the movie, Django has a bundle of dynamite strapped to the front doorframe of Candie's house and uses it to blow up the place. The explosion caused by that bundle was way too large compared to the amount of dynamite used. It also shows the house exploding from the center out, distributing debris almost equally in all directions. But the dynamite was at the front door so most of it would have gone backwards.
Continuity mistake: When Django and Dr. Schultz ride into Daughtrey, Texas. In the town there is a kid with some goats. There are goats behind and in front of Django and Dr. Schultz. When they change angles all the goats are in front, with no goats behind them. (00:14:10)
Continuity mistake: In the first shot of Stephen writing a check to the Harris Feed Co: The "i" is connected to the second "r", the numeric dollar amount is "68.00" (with the period barely visible), the written dollar amount is "Sixty Five", and in the year of the check, "58", the numbers are touching and the "5" looks somewhat like a "6." Seconds later, in the next shot, which is more of a closeup of the check: the "i" is no longer connected to the second "r", the numeric dollar amount is now "65.00" (with the period very visible), the written dollar amount remains as "Sixty Five", but the handwriting (as with the rest of the check) is somewhat different than in the 1st shot, and the year is now written as "58", with the numbers no longer touching and the "5" looking like a "5." (00:01:25)
Continuity mistake: Django's first shot at the snowman that puts a hole in the bottle/can. His gun is pointed way too high when he shoots it to hit the target. (00:55:50)
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.
Factual error: When they enter the big house after the funeral, Sam Jackson is singing "In the sweet by and by", the song was written in 1868, the film is set 10 years earlier.
Continuity mistake: When Calvin is explaining stuff about the skull, Schultz's glass swaps from empty to filled, between shots.
Continuity mistake: When Django takes cover by the hallway, several guys shoots at him from the doorway, making the wall behind him riddled with holes. The next shot, no holes. These holes disappears and reappears several times. (02:12:30)
Continuity mistake: When Calvin Candie talks to Dr Schultz about his "first, second, third, fourth & fifth concern", his sister Lara puts her glass down on the table, only to have it in her hand again immediately afterwards.
Continuity mistake: When Django gives himself up, the body that he used as a human shield moves from the centre of the door frame to the left of the door frame.
Continuity mistake: When Django and Dr. King Schulz meet Spencer Bennett at the front of his house, there's a group of women and some men in the back near the gates. The amount of people changes between shots. (00:29:10)
Other mistake: When Schultz meets the Speck Bros. visible breath comes out of the slaves' mouths due to the cold, but not from Schultz or the brothers'.
Revealing mistake: When Ellis Brittle lays dead on the cotton field, a blood pack visibly protrudes from his chest.
Continuity mistake: At the start of the movie, Christoph Waltz shoots the horse in the head, but later the bullet hole is seen in the horse's neck.
Revealing mistake: When Django kills big John Brittle, right when he smashes his face on the floor, a cushion pops-up. Most probably hidden among the leaves to soften the fall.
Chosen answer: There is nothing in the film to indicate that he is not. He has the paperwork to prove the bounty he was pursuing, and he is not held by the authorities or charged with any crime, so we can assume that he was.