Starring: Frank Welker, Don Messick, Casey Kasem, John Stephenson
Vampire Bats and Scaredy Cats - S2-E2
Other mistake: When the Mystery Company find a torn paper in a coffin, it is written exo-6 and something else. They find later that exo is the first part of exotic. The way the paper was torn, you should be able to see the lower part of the missing letters.
Hang in There, Scooby-Doo - S2-E3
Continuity mistake: In the cavern, Scooby and Shaggy dig holes in the ground. The rest of the group notice a truck driven by the Pterodactyl going toward them. Discs and cassettes fall from it. The shot later, the stones behind them have disappeared and the pile of discs have a different shape.