The opening scene contains a rare example of both Velma and Daphne wearing bikinis (which are the same colors as their daily clothing). Fred wears an ascot even when he is otherwise topless.
Scooby's attempt to retrieve the red jewel, setting off the booby trap despite all precautions, resembles the opening scene of Raiders of the Lost Ark (1981). A later movie in that series, Indiana Jones and the Kingdom of the Crystal Skull (2008), used the "ancient astronaut" theme.
"Ancient astronauts" (or "ancient aliens") is to a pseudoscientific hypothesis that intelligent extraterrestrial beings visited Earth and made contact with humans in antiquity and prehistoric times. It gained popularity in scholarly circles in the 1950s, but was largely forgotten as a serious theory by the 1980s when this cartoon aired. However, it has never gone out of style in adventure fiction.