Air date: August 10th, 2003 (JP), February 7th, 2004 (US)
Tropes:
- Adaptational Villainy: In the original version and tie-in comic book, King Boom Boo and the other ghosts are the original owners of this castle who humans woke up and just want to teach the trespassers a lesson, make them leave the castle's grounds and then return to sleep. In the original game, King Boo is also an Anti-Villain who just wants to expel the trespassers.
- All Part of the Show: Chris' mother Lindsay thinks that all the supernatural activity going on in the castle is all part of the movie she is working on, much to Chris and his friend's annoyance.
- And I Must Scream: Ella, Cream, Cheese, Tails, and Sonic being trapped in the otherworldly void in the walls with the ghosts. The other victims are unconscious but in Sonic's case, he's still able to see what's going on outside and scream out to Amy Rose and Chris but with no luck. Same goes when King Boom Boo takes control of his voice to manipulate Amy.
- Anti-Villain: Type IV. In the Japanese original, the ghosts just want to return to sleep and just playing with the heroes so they'll leave the castle and his grounds.
- Demonic Possession: Amy gets possessed by one of the Boom Boos, making her attack the heroes.
- Enslaved Tongue: King Boom Boo's ability to talk through someone else's voice and use his words to manipulate victims to doing his evil bidding.
- Game Face: The Boom Boos have black eyes and a stitched-up mouths, making them look rather harmless, but their eyes change into red and yellow and their mouths reveal their black sharp teeth.
- I Have You Now, My Pretty: King Boom Boo holding Amy Rose captive in his grasp and allowing her body to become possessed by one of his ghosts.
- Nightmare Face: Amy after a Boo possesses her.
- Not Afraid of You Anymore: Amy says this to the boom boo trying to scare her before hitting it into a wall.
- Oh, Crap!: Many people's reactions when encountering the ghosts in the castle.
- People Puppets: Amy Rose being possessed by a ghost and used to attempt to stop and possibly harm Chris.
- Uncertain Doom: In the English dub, the man who built the castle on, unbeknownst to him, haunted grounds. When told by the civilians about the ghosts haunting said grounds the castle is built on, he laughed and said they were nonsense. After spending his first night inside the castle, he mysteriously disappeared never to be seen again. And there are ghosts laughing inside that castle still to the present day.
- Wham Line: The policeman to Sonic and his friends: "No one's been able to escape any of the ghosts before!"
