Corrected entry: In the gunfight scene at the end almost at the exact point of the discharge of the guns, if you look in the distance to the left of Indio you will see a white vehicle travelling along a road from the left to the right.
Corrected entry: When Lee Van Cleef shoots his rifle at the man escaping on the horse, he is right next to his own horse and a rifle shot that close to a horse would cause it to rear or be startled. The horse is not startled, even when a second time Cleef shoots his pistol. The horse does not react.
Correction: The Colonel' s horse belongs to the "best shot in the Carolinas" a bounty hunter and conceivably served as his horse in The Civil War. It is entirely plausible that his horse was much more used to gunfire than a grain bag. My sisters thoroughbreds (a notoriously skittish breed), barely start when they hear my 12 gauge after a few years' exposure.
Corrected entry: During the nighttime "hat-shooting" sequence, Lee Van Cleef is shooting at Clint Eastwood's hat in mid-air. When Lee is finished shooting, Clint looks up and watches his hat fall to the ground. There is a person whistling as the hat is "falling" and then a sound of a body hitting the ground off-screen.
Correction: I think that is the sound of the hat flying through the air since it is full of holes and the sound of the body is the hat hitting the ground.
Correction: Checked frame by frame, no car to be seen.