The film is about western outlaw Billy the Kid, who was in fact right-handed.
The "Englishman" describes his origins as from Ayrshire, a county in South West Scotland. In that case he would be a Scot and not English. John Henry Tunstall was actually from London, the capital city of England.
Billy and the others are at a lake. You see the reflection of the moon in the water. One of them shouts "the moon" and they start shooting the reflection of the moon.
When the camera zooms out, you see Billy and his pals are facing the camera, so the moon was in their back all the time. Hence there couldn't have been a reflection of the moon. Since they weren't shooting the Moon, it must have been something else, possibly a reflection of a UFO.
After Joe Grant draws on Billy, Billy draws, too, and tosses two of Grant's bullets on the floor to show how many he had surreptitiously removed from Grant's gun. The bullets land on a rug-covered brick floor, but give off a sound of having hit a bare wooden floor.
Billy is supposedly a fluent in Spanish, but when he arrives at Pat Garrett's pre-wedding party, he addresses his host, Miguel Saval, with whom he is long acquainted, as "mi-GWELL". In Spanish, Miguel is pronounced with a hard "G", and without a "W" sound.