While on a boating trip, the gang crash onto Haunted Isle and go searching in the ancient Vasquez Castle for help.
This episode includes examples of the following tropes:
- Affably Evil: After the Vazquez castle ghost is revealed to be an ex-illusionist Bluestone the Great, rather than giving a You Meddling Kids speech, he actually manages to be gracious enough to give an encore performance showing how he managed the intangibility illusion and is quite cooperative when the police take him away.
- Bedsheet Ghost: The Phantom of Vasquez Castle. He has the ability to float around and go through walls, making his simple disguise more effective and scary.
- Early-Installment Weirdness: When Daphne is separated from the gang, she is shown to be very independent enough to avoid danger despite being best known later on as the designated Damsel in Distress.
- Expospeak Gag: Velma translates her own fancy talk in a joke at the beginning.Velma: When the barometric pressure dropped and the warm offshore air came in contact with the midland cold front, we ran into some unnavigable nucleation.Fred: You're right, Velma, whatever you said.Velma: I said, we're lost in a fog.
- Foot Bath Treatment: Scooby uses a foot bath (and a blanket) to pretend he's got a cold so he won't have to sniff out the Phantom. Naturally, the humans don't fall for it.
- Haunted Castle: The old Vasquez Castle, where the gang ends up stranded.
- Human Disguise: The gang attempts to pass off Scooby-Doo as a human when using him as the bait to trap the Phantom, by dressing him in a trenchcoat, a bowler derby hat and a fake mustache.
- Hypocritical Humor: At one point as Scooby and Shaggy are wandering the Vasquez Castle together, they are both whistling to try and calm themselves down, but then Shaggy stops and tells Scooby, "Stop that whistling! You make me nervous!"
- Monster of the Week: The Phantom of Vasquez Castle.
- Nutritional Nightmare: In the opening scene, Shaggy prepares a double-triple-decker sardine and marshmallow-fudge sandwich, complete with an olive on top. But Scooby-Doo ends up eating it before Shaggy can take a bite.
- Saw a Woman in Half: Shaggy appears to fall victim to this, with the saw working on its' own into the box. But when Velma rushes to the rescue it's too late... only it turns out Shaggy's head in one half of the box is just a dummy head in Shaggy's likeness, and Shaggy is still in one piece cramped up inside the other half.Velma: Hey! This is just a dummy head!Shaggy: (popping out of his half of the box) Someone mention me?
- Stranger Behind the Mask: Unlike many traditional Scooby-Doo mysteries, the villain under the ghost/monster costume is someone the gang had not met before The Unmasking, in this case, ex-magician Bluestone the Great. The sheriff that comes to arrest the villain recognizes him and fills in the gang on who he is.
- Tempting Fate: Daphne dismisses Velma's statement that a castle is filled with traps, but then ends up falling through a trap door.
