Question: The road leading up to Minnie's has been freshly plowed when the stage arrives. It is obvious because there are sharp borders at the edge of the road and no tracks. Did the bushwhackers plow the road to eliminate evidence of their nefarious deeds?
Answer: Yep, gotta be a mistake. If they even had snow plows back then, the plow would have had to been between the bad guys and the stage and would have arrived, or passed by, at a very inopportune time. I think the director just missed this, or didn't think anyone would notice.
Answer: Think you mean the plow would have arrived before the stage. But yes, a mistake for sure.
Question: Was the poison that killed both John Ruth and O.B. (by causing them to vomit blood) purely fictional? Does it have any equivalents in the real life? If it does, then what kind of poison was that?
Answer: It's not PURELY fictional, as plenty of poisons lead to vomiting and bleeding (cyanide, arsenic, etc.), but Tarantino, as is his wont, definitely takes some artistic license and kicks it up several notches for dramatic/gross-out effect.
Question: I know it was never really found out, but was Chris Mannix really the new sheriff of Red Rock?
Question: Was Warren's story about general Smithers' son real, or he was merely making it up in order to provoke him?
Answer: It's honestly been up for debate ever since the film came out, and people still don't have any real consensus. So I don't necessarily think there's a "right" answer. I personally think there may be a kernel of truth to it, but that he also embellished the story greatly to provoke Smithers. (Ex. I wouldn't be surprised if the sexual assault was completely fabricated).
I think that this story is at least partially true because Warren knew the full name of Smithers' son.
Question: Maybe I saw it wrong since it happened so fast, but wasn't Minnie shot in the face initially when she was behind the counter? If so, surely she wouldn't still be alive, yet she was still alive when seen a little later on the floor where she is shot again in the stomach/chest.
Question: Why was John Ruth treating Daisy Domergue so violently? I mean he was beating her up quite frequently.
Answer: He has a bad temper and despises criminals.
Answer: Good catch! This should be a revealing mistake entry. The plowing was part of the set preparation. I saw several scenes in the film where the roads had obviously been plowed. It's not hard to see if you look for the small ridges left by the plow on either side of the road.