According to "Wildest Westerns Magazine", Peter Breck was able to draw his gun in 16/100 of a second, making the character of Nick Barkley the fastest draw in television history.

There was originally a fourth Barkley son, Eugene (Charles Briles), who appeared in eight episodes of the first season. Briles was forced to leave the show midway through the first season because he was drafted by the U.S. Army. After leaving the regular cast, Eugene never returned in later seasons, even when Briles mustered out of the Army, and basically, Eugene was never really referred to again.

Victoria (Barbara Stanwyck) is the only Barkley who was never shot throughout the run of the series. Heath (Lee Majors) was shot the most, and Nick (Peter Breck) has the distinction of being the only Barkley who is shot twice in the same episode.

The series was cancelled despite its popularity, because the networks were phasing out westerns in favor of more modern television shows.

Dell Comics published a six-issue comic book series based on the series from 1966 to 1969.

The series was loosely based on the Hill Ranch, which was located on the western edge of Calaveras County in California. Lawson Hill started the ranch and ran it until his death in 1861. He and his wife Euphemia had four children, three sons and one daughter.

This was the only western to be built around a strong, female lead character.

In every episode where Nick (Peter Breck) is a spectator in a court case, he interrupts the court to speak his peace, which always gets him into trouble with the judge who is presiding. In later episodes throughout the series, this took on a comedic tone, as the viewer knew that it was only a matter of time before Nick would voice his displeasure.

Heath's (Lee Majors') horse was named "Charger".

The jailhouse set was the same one used in Gunsmoke (1955).

With the February 6, 2012, death of Peter Breck (Nick) and the June 12, 2016 death of Charles Briles (Eugene; only eight appearances during the first season), there are only two regular or recurring cast members with more than twenty appearances on the show, Lee Majors (Heath) and Linda Evans (Audra).

Linda Evans went over every Saturday to Barbara Stanwyck's house to work on the scenes together to the point where Linda began to think of Barbara as her mother.

Of all of the leading cast members, Barbara Stanwyck was the only one nominated for an Emmy. She was nominated during each of the first three seasons of the show, and won her first nomination.

The exterior shot of the Barkley house shown in the opening theme was the same house exterior used for Tara in Gone with the Wind (1939).

Jarrod (Richard Long) was the only one to ever get married. It only lasted a few days after only meeting a week before. She died accidentally taking a bullet for Jarrod when leaning over to pick a flower while picnicking beside a stream where their future house was going to be built.

Victoria's horse was "Misty Girl", while Nick rode "Coco".

The entire family, minus Eugene (Charles Briles), have all killed throughout the show. Audra (Linda Evans) killed two men during the first season; Nick (Peter Breck), Heath (Lee Majors), and Jarrod (Richard Long) killed many people throughout the series, and Victoria (Barbara Stanwyck) killed at least two people in each season.

Throughout the series, Lee Majors was always introduced as Heath in the credits, no last name. This was because, even though he was accepted as a member of the family, there was always the question of whether he was a true Barkley or not.