When Dingus tackles Anna off of her horse following the chase after she threw her knife at his wanted poster, a stunt double for Anna, wearing skin-colored tights, falls off the horse.
In several shots during the cavalry troop scene, Anna is replaced by an obvious stunt double wearing skin-colored tights, including when Dingus and Anna run their horses into the wagon 'half-moon', and when driving the gunpowder wagon away from the cavalry.
When Sheriff Birdsill (George Kennedy) drops his cigar near the gunpowder, it flares up about a foot away from the cigar and then burns toward it.
Frank Sinatra is obviously wearing a wig.