Goofs

When Doc Holliday shoots Billy the Kid in the hand, we see a bleeding wound. In subsequent scenes, his hand is completely fine.

Billy prepares to settle down for the night in a livery stable, goes across to put the lantern out but it goes out before he can blow it out.

When Guadalupe (the older woman) first appears in the shack where Rio is tending to Billy, she has two long plaited pig-tails. Things continue in real-time and after a few views of her with pig-tails, she suddenly appears after a cut with her hair up in a bun at the back.

Doc Holliday changes position several times between shots during his first conversation with Billy the Kid.

Billy the Kid was killed by Pat Garrett in 1881, but Doc Holliday died in bed of tuberculosis in 1887.

The grave marker at the end of the film gives July 13th as the date Billy was killed. In fact, he died on 14th July.

Doc Holliday was only 29 at the time of the events depicted, yet is played by 57-year-old Walter Huston.

The following morning, Billy meets Doc Holiday and go to the saloon where they order breakfast. A cowboy asks to speak to Billy in a back room where he tries to maneuver Billy into a position to kill him but Billy beats him to the draw. A while later, Pat Garrett and his deputies enter the saloon to investigate the shooting and it can be seen by the sky in the background that it is now night.

In the final scene, a car can be seen in the distance passing from left to right.

When Doc takes wounded Billy to Rio's place to recover, at one point Rio removes her shoes in the bedroom, and rolls down and slips off what look like nylon stockings. These didn't exist in 1880 New Mexico, debuting instead at the World's Fair in 1939. This film was made in 1941.

(at around 1 min) As Doc and The Kid are leaving the stable, they both walk into the camera shadow on the right side of the screen.

Joshua trees (Yucca brevifolia) appear in several scenes. Joshua tree occurs in southeastern California (mostly, southern Nevada, northwestern Arizona, and extreme southwestern Utah, but not in New Mexico, where the story takes place.