Revealing mistake: When Gunnar lifts Vaca over his head during the fight, in the closeup he's holding up a barrel over his head instead of Vaca and throws the barrel. (00:35:05)
Continuity mistake: Little Joe is bitten on the right hand by a gypsy in a bedroom. He exits the room rubbing his left hand which is examined by Ben and Hoss. (00:07:00)
Found Child - S7-E7
Factual error: The episode opens with Hoss discovering a wrecked wagon with three dead adults. He spots a Raggety Ann doll and realises that a child may be nearby. Raggety Ann dolls weren't invented until 1915, at least 48 years after the shows time frame.
Continuity mistake: When Ben comes in the house he's carrying his coat. When he passes Adam he doesn't have it. When he goes into Hoss' room he's got it in his hand again.
The Rescue - S2-E23
Continuity mistake: When Ben is shot at he falls on his right side. When the shooter goes to check it out he's on his left.
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.