Cal Wayne startles Grant Evers when he tells him that he killed his brother, but later on in the picture, Grant states that he had word that Dave was dead.
When the whipped Cord is on his horse and Cal is trying to catch him, the man from a distance has blood smeared all over his back, but up close after being caught, Cord's back only has dried blood stripes and no smears.
When Slade kills Grant with the last two shots, he stands over him and lets his pistol hang limp from his hand while he pulls the trigger. The pistol doesn't kick at all, it barely even moves, proving that it's firing blanks. A loaded gun would have kicked out of his hand, being held that loosely.
Bobby Darren enters the town; his cigar is clearly fake as no smoke comes out. Later, he is briefly puffing on a real cigar.
Bobby Darren walks to the Grant-Evers office he is holding a cigar in his hand. When he enters the office, the cigar is gone.
The majority of the men shown are clean shaven. While beards were not common, mustaches were and at least 50% of the men would have worn them.
The clothing worn by the characters in the film resembles modern Western wear more so than post- Civil War dress. This includes pants with belt loops and shirts with buttons down their entire fronts. Bobby Darin's cowboy hat was the style worn with suits in the 1950s.
The bar hostess is not only wearing colors which would be uncommon for clothing in 1860s America, she is wearing a short sleeve blouse. Due to illnesses and injuries leaving scars as well as the standards of modesty at the time, few people showed any skin beyond their necks, faces and hands.
Women riding on wagons or coaches in the Old West covered their to prevent dirt and road dust from getting in it as well as to protect their faces from the sun. In this film, the women do not despite riding for miles on dusty roads.
When Grant Evers (Leslie Neilsen) straps on his left-handed gun belt and starts practicing his fast draw in his basement storeroom, his first shot starts two different targets spinning at the same time, and the third one a split second later, all before the sound of the third shot.