Although Billy was only 22 at the time of his death, star Donald Barry shows a growing paunch and looks every bit his 38 years. In reality, Billy was 21 when he was killed.
Although the film claims Billy killed 22 men and varying popular accounts put his death toll as high as 26, most historians believe the actual number to be between four and nine.
The infamous incident involving Billy the Kid and Joe Grant in the Fort Sumner saloon is portrayed differently here. Grant's misfire is generally believed to have been caused by his firing the traditionally cautionary empty chamber. Billy reacted by fatally shooting him in the chin. In this film Billy uses sleight of hand to remove the bullets from Grant's gun prior to his firing it, contemptuously giving him a backhanded slap across his mouth and chin after the misfire, and leaving the saloon without killing him.