The gang investigates the Darrow's old mansion that is hidden under the foundations of Darrow University. While they are there, someone keeps trying to trap them, referring to them by the names of the old Mystery Incorporated members.
The episode has examples of:
- Ambiguously Evil: At the end of the episode, while the Mystery Inc. discusses about the possibility of there being multiple pieces, they wonder who else could be after the pieces. The camera pans out to show Mayor Jones listening in on their conversation before driving away.
- Chaste Hero: After Fred pulls Daphne from the villain's swimming pool trap, she pretends to need artificial respiration. She's expecting mouth-to-mouth... he presses on her stomach instead.
- Earthquakes Cause Fissures: The cold open starts off with this during a flashback, swallowing a mansion up underneath it. An earthquake appeared at the end of the episode, but it's not stated what happens after that.
- Even Bad Men Love Their Mamas: Danny Darrow is a crazy, psychotic Trap Master. Yet even long after she passed away, he still loves his mother so much that a person can trick him to believing she's still alive.
- Foreshadowing:
- Danny has a look of relief when Scooby Doo pretends to be his mother, despite the fact she's dead. Cue Danny realizing the treasure he loved so much ruined his life.
- Danny calls Fred "Big-Chin Man" despite only seeing him now. Danny's not seeing Fred though; he's seeing his real father, Brad Chiles.
- At the end of the episode, now that they're in possession of a piece of the treasure, the Mystery Inc. wonders who else could be after the treasure while the camera pans out to reveal Mayor Jones is eavesdropping on them.
- Angel says that Cassidy Williams' diary was left on her doorstep by Mr. E, but it lacks Mr. E's signature seal on it. This is because Angel is Cassidy Williams and just had the journal with her.
- Formula-Breaking Episode: The first episode of the series to depart from the Monster of the Week-"Scooby-Doo" Hoax formula, instead having the gang discover the sunken Darrow mansion and navigate its traps, led along by a mysterious voice.
- Not Wearing Tights: The villain this time around is not hiding in a costume or a mask. He doesn't reveal his identity because he believes he's dealing with the original Mystery Incorporated.
- Redemption Equals Death: Danny Darrow, the last survivor of the Darrow family, had booby-trapped his mansion in order to keep hold of a clue to the Haunted Treasure. Upon realizing that he'd wasted his life, he told the gang to take it and escape from the collapsing dwelling. His last words were "I hope it brings you more happiness than it ever did me."
- Reduced to Ratburgers: Scooby finds a bubbling pot over the fire in Danny Darrow's hidden room with rat tails hanging over the sides.
- Small Name, Big Ego: When Velma, Scooby and Shaggy are in a trap, it states that only the smartest of the group could get out. Velma assumes it's her... until we see that the one who created the trap isn't seeing 'Cassidy' as the smartest; it's 'Pericles'! (Scooby). Velma tries to hide the fact that she made an error once they're free.
- The Tape Knew You Would Say That: Parodied where the villain tells Fred and Daphne that his message is pre-recorded and can't answer their questions, but then they point out that he had already answered a question, ruining the charade.
- Take a Third Option: Fred and Daphne's scenario involves the means for Fred to escape and leave Daphne behind to drown in the swimming pool while chained down, but there's a large rock intended to weigh him down and die with her. Fred just uses it to smash the chains.
- Torture Cellar: The several knife-trapped rooms have this vibe.
- Trap Master: This episode had Fred pitted against another, villainous trap master, in which he treated him as if he were the ultimate rival. Which leads to a great moment when they start discussing different types of traps.
- Trash the Set: At the end, all of the traps going off triggers the fault line and tears the mansion apart.
- Wham Shot: While the gang discusses who else could be after the treasure, the camera pans out to Mayor Jones listening in on their conversation before driving away.
- Whole-Plot Reference: The episode shares many similarities to the Saw movies. The climax — where the MacGuffin is found and the earthquake begins — resembles Indiana Jones and the Last Crusade.
- Worst Aid: Averted. Fred points out to Daphne that mouth-to-mouth doesn't work when your lungs are filled with water.
- Worthy Opponent: Fred gets really excited when he realizes they're dealing with another skilled Trap Master. After he's captured, Danny acknowledges Fred is worthy as well.
- Fred: Question is, are there other pieces out there? And if there are, who else is looking for 'em?
