Continuity mistake: A flashback episode set in the 1840s opens with Ben Cartwright as a first mate aboard a clipper ship. Rear-screen projection shows an ocean and a grey overcast sky. In a shot of the crew on the rigging and in the crow's nest, the sky is deep blue with a few white clouds.
Factual error: In a flashback episode set in the 1840s, Ben Cartwright and his former Captain are operating a ship's chandler business. A competitor accuses them of running a "flea market." That term is a translation of the French "marché aux puces" and did not enter the English language until 1922.
Factual error: Joe Cartwright gives a Raggedy Ann doll to a young woman named Annie. "Bonanza" is set in the late 1860s. The Raggedy Ann character was created by Johnny Gruelle in 1915.
Character mistake: Jamison Filmore reminds a steamboat captain that they were in prison together in "Cell 241." Five minutes later, he says they shared "214."
Continuity mistake: The sheriff of Morris Flats suspects Adam of being a bandit and puts him in jail. The window of Adam's cell has four vertical bars, but when the "knight" comes to talk to Adam from outside the cell window, the window has five vertical bars.
Continuity mistake: Laura Dayton is at a party at the Ponderosa but leaves and goes outside because she has a headache. Ben Cartwright's brother Will comes out and says he'll take her home via horse and buggy. It is night and the sky is dark, but when they reach Laura's house, it appears to be early evening. The sky is much lighter and the trees are casting long shadows on the ground.
Other mistake: Outside the Pine City marshal's office is a painted backdrop depicting some two-story blue-and-white buildings. The same backdrop is seen from the Virginia City saloon. It also appears in another town in the episode "The Legacy."
Continuity mistake: Adam and Joe are restraining Hoss while Ben gives him a ladleful of a thick white tonic for "spring fever." Joe has his right arm around Hoss' neck and is holding Hoss' mouth open with his left hand. As Hoss takes the tonic, a glob of it spills onto his left cheek. In the immediate close-up, the glob has vanished.
The Legacy - S5-E11
Other mistake: Adam stops at the Wild Horse Saloon in a nearby town, seeking information about a man who he mistakenly thinks has killed Ben. Outside the saloon is a painted backdrop depicting some two-story buildings. It is the same backdrop seen from the saloon in Virginia City.
Factual error: This episode is set in 1861. A little girl, Peggy Dayton, has a Raggedy Ann doll. Johnny Gruelle did not create the Raggedy Ann character until 1915.
The Guilty - S3-E23
Continuity mistake: Ben Cartwright agrees to meet a man at the land office at 9:00 the following morning but when Ben arrives at the office the next day, the time on the wall clock is 5:47. In a scene that takes place a few minutes later, the clock still says 5:47.
The Unwritten Commandment - S7-E28
Factual error: Wayne Newton sang "Scarlet Ribbons." "Scarlet Ribbons" wasn't written until 1949. The TV show Bonanza was set in the 1860s.
The Hostage - S6-E2
Other mistake: A gang kidnaps Ben Cartwright and holds him for ransom. He is chained to a post in an abandoned mine. When the men walk around inside the mine, the sound of their footsteps make it obvious that the floor of the mine is actually plywood covered with a layer of dirt. Additionally, when Ben finishes eating stew that was brought to him and sets the container down, it makes a loud "clunk."
Other mistake: Ben and Little Joe do not see the horse belonging to Ben's brother Will, who is staying with the Cartwrights. Joe says, "I'll see if he's in his bedroom." Joe is out of the scene for only five seconds, then returns and says, "He's not there." Five seconds is not nearly enough time to go upstairs, check a bedroom and come back downstairs.
The War Comes to Washoe - S4-E7
Other mistake: In early evening, Hoss and Adam discover the body of a man who had been shot with an arrow and killed. Even though it is still very bright sunlight, Adam lights a match and holds it close to the man's face so he can see who it is, then lights another match so he can read a letter that was in the man's coat pocket.
Continuity mistake: When Adam goes after Howard, he doesn't have his jacket on. When they sing "Endless Road," he is wearing his jacket again.
Continuity mistake: In The Beginning of the movie, Adam goes from wearing a black shirt to a yellow jacket after he fights the man that stopped the couple on The Wagon.
