The Dog Who Knew Superman - S2-E9
Other mistake: A gangster pushes a dog into a well and the dog can be heard splashing around. The man's wife is furious and several people are unable to retrieve the dog. Superman tunnels into the ground and into the bottom of the well and emerges holding the dog. Both he and the dog are completely dry.
The Fall Guy - S1-E4
Character mistake: Thorny tells Ozzie that Clara Randolph is throwing a party. When Ozzie tells David and Ricky about that party, he calls her "Mary Randolph."