The Creepy Heap from the Deep - S2-E8
Audio problem: When speaking about the hidden beauty parlor in the submarine Velma's voice comes from Daphne's mouth briefly.
The Scooby Doo Show (1976)
1 audio problem in season 2 - chronological order
Starring: Frank Welker, Don Messick, Casey Kasem, John Stephenson
Continuity mistake: In the episode of Scooby movies where they meet the Three Stooges, Fred says that Velma is missing and they need to find her. When they go off to look for her they pass a window. Fred first, Daphne, then Velma (despite her being the one missing!), Shaggy, then Scooby.
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