Revealing mistake: Samuel Clemens (Mark Twain) spends a night in North Fork while the wheel of a stagecoach he is riding in is being repaired. Clemens is fishing at a lake and Mark McCain says, "You've caught a fish " Clemens tells the boy to reel in the fish. The boy jerks the rod and pulls the fish out of the water. The fish is obviously a fake which a stagehand had attached to the hook. The fish is motionless and is not even wet.
The Rifleman (1958)
1 revealing mistake in season 4 - chronological order
Starring: Chuck Connors, Johnny Crawford, Paul Fix
Revealing mistake: Two former Civil War officers prepare to make camp in a sandy area surrounded by large rock formations. It is obvious that they are on an indoor set. As one man takes a few steps, the sound of his boots hitting the wooden platform beneath the sand can be heard.