Continuity mistake: Lucas, Micah and Joe are riding to the home of Old Tony and the sleeves of Lucas' long-sleeved shirt are rolled up. In a long shot, as Tony watches the men approach, Lucas' sleeves are down. In the following close-up, the sleeves are rolled up.
Other mistake: At the beginning of the episode, Lucas and Mark are riding their horses and discover a large footprint of a cougar. Near the end of the episode, Lucas is riding in a different area and sees another cougar footprint. The close-up of the footprint is the same one that was shown earlier. (00:01:00 - 00:21:00)
Requiem at Mission Springs - S5-E22
Other mistake: After Mark falls from a horse and is paralyzed, Doc Burrage recommends that Mark soak his legs in the Mission Springs mineral spring. Lucas, Mark and Lou drive a wagon to the site. At night they all complain about how cold it is and there is a steady sound of wind blowing but all the trees and bushes are motionless.
Quiet Night, Deadly Night - S5-E4
Character mistake: Nils is playing checkers with Mark. Nils calls him "Mark" then "John." (00:20:35)
Suggested correction: He says "now", not "John." After he Mark says he remembers it like it was yesterday, Nils says "go on, it's your move now."
Factual error: Ralph Hayden hires Mario Rosati to kill Lucas McCain, who had shot and wounded Hayden many years before. Hayden says McCain previously lived in Enid, Oklahoma. "The Rifleman" is set in the 1880s and Enid did not exist until 1893. (00:01:10)
Factual error: Lucas and Mark are traveling on what is said to be the first train to ever reach the town of North Fork. The episode is set in the 1880s and the train shown was part of the M.K. & T. Railroad, which at that time was operating only in Missouri, Kansas, Texas and Oklahoma. The fictional town of North Fork is located in New Mexico Territory.