Plot hole: Given it's a government building there's no way the ghosts could drill into the U. S. Mint and not draw security's attention.
The Scooby Doo Show (1976)
2 plot holes in season 1 - chronological order
Starring: Frank Welker, Don Messick, Casey Kasem, John Stephenson
Vampire Bats and Scaredy Cats - S2-E2
Continuity mistake: When Lisa's uncle shows her her grand-father's picture, it changes from one shot to another.
More trivia for The Scooby Doo Show