A Matter of Circumstance - S11-E28
Continuity mistake: It is obvious that a wind machine was used in the opening scene. Dust, straw and leaves are blowing across the Ponderosa and trees in the foreground are swaying but the trees in the background are motionless. Two minutes later, a shot of a cloud-filled sky and a flash of lightning is shown and rain starts falling. In the next shot, Joe is inside the barn and sunlight is streaming through the windows even though rain is falling. Joe's horse then gets spooked by a lightning bolt and knocks Joe to the ground. The horse tramples him several times but when Joe is finally able to get up, the back of his shirt and pants are completely clean.
Continuity mistake: Hoss Cartwright's hair is medium brown in the scenes which take place at the Ponderosa, but in all other scenes his hair is a very dark brown, almost black.
The Lady and the Mark - S11-E18
Continuity mistake: A young woman named Charity is fishing from the shore of a lake. The water is a deep blue color and there are no rocks. When she gets a bite, the close-up shows a fish flopping amid several rocks in shallow blue-green water.
Continuity mistake: Ben Cartwright and a man named Gunny are driving a team of six horses and a wagon in a race with two other men with a six-horse team and wagon. The winner will get a contract to transport mail. During a part of the race which goes through a dense forest of 40-foot-tall pine trees, a close-up of Ben and Gunny shows only blue sky and no trees.