Stupidity: Why would Gabriel have an item as valuable as the Poison Pill dangling from his neck (and therefore susceptible to falling off or being snatched by Ethan) during the airplane sequence rather than have put it in a secure location like a closed pocket before takeoff?
Stupidity: During the raid on the compound, the kids are being loaded into the bus and are about to be driven to a mass grave. Chris and Braxton know that’s the plan, but don’t even try to shoot the tyres on the bus to make it undriveable. They’re both excellent shots and could have done it without any more risk to the kids than the firefight already going on around them. Instead, they just watch the bus get driven away.
Stupidity: The confrontation in the rain between the two brothers lacks basic logic. As Thomas himself points out, nobody should ever entertain the thought of believing whatever Robert has to say, since he already unilaterally broke the safe passage agreement he proposed earlier. Robert's motive should be that he wants Thomas alive, but then again it turns out the objective of this ploy was to have some of his men sneak up on Thomas, guns in hand. He obviously had no need for his armed men to sneak up on his target already in plain sight, if all he wanted was to kill him.
Stupidity: The Klansmen arrive at Club Juke in the morning. Hogwood orders one of his boys to open the door, and the guy finds it closed shut. He's quite surprised, saying, "Door's locked!" In the reaction shot on Hogwood, you can plainly see on the actor's face and hear in the delivery of the line that the character is supposed to be incredibly surprised by that. Granted that they may not be quite privy to the traditions of the coloured folks, and that racists are kind of dumb to begin with by definition, but what sort of imbecile would show up at a night club early in the morning and expect it to be open? You won't even find most pubs open at 9 AM on a Sunday, let alone a barrelhouse.