Corrected entry: When Big Jake falls in the mud early in the movie (I think he's fighting one of his sons), his clothes are clean and dry immediately afterwards.
Corrected entry: After the gunfight in the hotel room where the bad guys try to steal the strongbox, the Duke returns to the room and the box is now open, revealing the contents. Sam Sharpnose says, "Shotgun blast broke the lock, Jacob." But the bad guys didn't have shotguns, they had revolvers. Michael had a shotgun, but the lock was facing away from him.
Corrected entry: The Duke's 8-year old grandson tells the Duke that he has never fired a gun before, but when the Duke gives him the derringer, the kid cocks and fires both barrels like an old pro.
Corrected entry: The Duke asks his estranged wife Martha for a piece of clothing the kidnapped grandson had worn recently (for his dog to get a scent of, presumably). However, the dog wasn't used at all for tracking. Sam Sharpnose tracked the gang.