Revealing mistake: On her first evening at the ranch Susannah watches Tristan breaking in a mare. When he falls on the ground you can see that he merely climbs off instead of being thrown. (00:18:00)
Revealing mistake: When Tristan takes revenge for his brother and scalps two German soldiers you can see that his knife just goes through the hair. (00:44:25)
Revealing mistake: When Tristan kill the guy in the liquor storage and the hay fork goes through his chest, you can see that parts of the hay fork's tines closest to his body are not covered with blood. (01:51:05)






Answer: Very early in the story when one stab is narrating, he's kind of introducing everybody and makes a reference about Decker having "illegally" married an Indian woman, and there are several references to the fact that the father was not happy working for a government that was killing Indians and also went out of his way to make sure they were in no way discriminated against. I think it's possible that may be why they were looking for Decker and why Colonel went out of his way to hide his living there.
I believe Decker had been a bootlegger. That would be the reason why the O'Banions (sellers of booze themselves), were with the sheriff when they came looking for Decker at the Ludlow's ranch. And also, the reason why the O'Banions didn't want to say what Decker was wanted for because.it was their own personal vendetta concerning bootleg whiskey. Maybe they had reason to believe that he was still selling bootleg whiskey around those parts. Also, later in the movie, when Tristan returns home after 7 years, Decker says to him "There's good money in bootlegging if you know what you're doing." And, Decker says that with a huge smile. Like he definitely knew what he was talking about and could definitely give Tristan some pointers about being a bootlegger.
Alcohol wasn't illegal until well after World War 1. The initial scene with the O'Bannons takes place before the boys go off to war, and it's stated afterwards that Alfred voted for the Volstead Act making alcohol illegal.
Not sure about this. At the time the sheriff comes looking for Decker, it's roughly 1915, and liquor is not yet illegal.