The gang stops to help a couple of runaway circus performers and finds that they're fleeing a mysterious ghost clown causing trouble in the big top.
This episode includes examples of the following tropes:
- Attack Reflector: When the clown tries to hypnotize Scooby and Shaggy with a revolving coin, they hold up mirrors to reflect images of the coin back at the clown and hypnotize him instead.
- Bungled Hypnotism: Shaggy's trap for the Ghost Clown. As the clown gets ready to hypnotize him and Scooby into acting like chimpanzees, they hold mirrors up so that the clown ends up hypnotizing himself instead.
- Circus Episode: The episode had a phantom clown with a hypnotic coin sabotaging a circus.
- End-of-Episode Silliness: As the episode ends, Barnstorm introduces Samson the strongman, who came back after the Ghost Clown was caught. Fred, Velma, and Daphne discuss a secret act Shaggy and Scooby have been working on. This turns out to be hiding in the hollowed-out balls of Samson's weight.Velma: What an act! It's great!Fred: [clapping] What a pair of hams! They're a riot!
- Even Evil Has Standards: Implied when the Ghost Clown puts Daphne under his spell as he only lets her ride restlessly on a unicycle (all while wearing a tutu and tiara), which could imply that he wouldn’t lead a beautiful girl like Daphne to her demise as he would to Shaggy and Scooby. This is dropped in the Gold Keys comic adaptation, however, where the Ghost Clown indeed plans on feeding Daphne to the lion.
- "Eureka!" Moment: Shaggy has one when Fred says he was so confident in his failed trap that he "would have bet money" on it working; Shaggy remembers the gold coin, realizes what happened, and comes up with the plan to capture the Ghost Clown.
- Evil Laugh: The ghost clown lets loose with a cackle as he prepares to leave Shaggy at the mercy of a lion. That gives Scooby just enough time to snatch the whistle intended to break the trance.
- Fanservice: When Daphne is put into the tutu and tiara.
- Go-Go Enslavement: Harry the Hypnotist, disguised as a Ghost Clown, hypnotizes Daphne. When next we see her, she's wearing a fanservicey circus outfit and performing a stunt on a unicycle.
- Hidden Depths: According to Shaggy, Daphne is incapable of riding a bicycle. And yet when she’s brainwashed by the Ghost Clown, she’s riding a unicycle with no problem.
- Hoist by His Own Petard: Scooby and Shaggy use mirrors as the Ghost Clown starts his brainwashing routine, causing the villain to hypnotize himself.
- Honorable Elephant: Scooby gets one to snap Daphne out of her trance with a spray of water.
- Hypno Fool: The Ghost Clown puts his victims into this state with his pretty coin of gold, making them perform circus acts (Scooby on the high-wire, Daphne riding a unicycle, and Shaggy as a lion tamer). At the end, he inadvertently becomes one himself when Shaggy and Scooby hold mirrors up at the last moment, and he obeys the command intended for them, acting like a chimpanzee.
- Hypno Pendulum: The Ghost Clown with his trusty golden coin and three of the gang members and even the Ghost Clown himself are victims of its power.
- Hypnotism Reversal: The Ghost Clown wreaks havoc by hypnotizing people with a coin on a string. Scooby and Shaggy defeat him by baiting him into trying to hypnotize them, then looking away and holding up little mirrors.
- Hypnotize the Captive: Daphne is again put in a damsel-in-distress scenario, only this time, she is trapped in her own mind when the Ghost Clown hypnotizes her. Ironically though, what the villain programs her to do is actually relatively harmless, riding on a unicycle (albeit non-stop and on a tightrope and some elephants that could very well cause her to hurt herself if she fell off) and is comically wearing a tutu and tiara, almost as if she’s a princess.
- Involuntary Smile of Incapacitation: The Monster of the Week hypnotizes Daphne, who ends up closing her eyes and giving a blissful smile when the villain starts programming her.
- Knight of Cerebus: The Ghost Clown is the first villain to actively try to kill the protagonists, making him the most serious Scooby-Doo villain at the time.
- Laser-Guided Amnesia: It’s implied that when a victim of the Ghost Clown’s hypnosis snaps out of it, they have little recollection of what happened to them as Daphne notes after she is awakened from her trance that she only remembers seeing the Ghost Clown’s hypnotic coin before everything went "blank".
- Laser-Guided Karma: The Ghost Clown is hypnotized by his own powers, at the hands/paws of Shaggy and Scooby, who he tried to make commit Psychic-Assisted Suicide.
- The Last Straw: Mr. Barnstorm outright calls it "the last straw" when he learns that Max and Samson took off and subsequently decides not to open his circus.
- Mind-Control Eyes: Zig-Zagged with Daphne as her eyes changed from simple black dots to blue eye color with white sclera when hypnotized and in the next scene, her eyes are turned back into black dots.
- Monster Clown: The villain of the story disguises himself as a ghost clown and ruthlessly employs his hypnotism to nearly kill Shaggy and Scooby.
- Motivation on a Stick: After getting the ghost clown to hypnotize himself into acting like a chimpanzee, Shaggy puts him on a leash and brings him to the rest of the gang so they can lock him in a cage. Scooby gets the clown to move with the aid of a bunch of bananas tied to his tail.
- Oh, Crap!: Samson and Max when they realize that their bicycle has been rigged by the Ghost Clown and are about to crash into each other.
- Panthera Awesome: The ghost clown hypnotizes Shaggy into acting as lion tamer, intending to undo the trance and let the lion eat him.
- Psychic-Assisted Suicide:
- The ghost clown attempted this on Shaggy and Scooby after hypnotizing them on separate occasions, only to be foiled both times. He made Scooby walk across a tightrope and then snapped him out of the trance when he was halfway across, but Shaggy was able to find something to cushion his fall. He turned Shaggy into a lion tamer and planned to snap him out of the trance and leave him defenseless, but Scooby was able to open the cage so he could escape.
- Averted with Daphne since he just lets her ride on a unicycle non-stop after putting her under his spell. It’s possible he just used her as a distraction to temporarily keep the gang from finding him. However, it could be downplayed since she’s seen riding on a tightrope and on some elephants and could’ve hurt herself if she fell down.
- Recycled Soundtrack: Some of the circus antics are accompanied by a circus-themed music cue lifted from Wacky Races. Then during the actual circus performance at the end, a circus music cue from The Flintstones and The Secret Squirrel Show is heard.
- Rule of Symbolism: Daphne smiling and closing her eyes after being fully hypnotized by the Ghost Clown is a sign that she’s fully surrendered to his hypnotic influence.
- Screw This, I'm Outta Here: The episode begins with Samson the Strong Man and Max the Midget, the circus's last two acts, leaving on a bicycle. Fortunately, once the gang captures the Ghost Clown, they (and all the other acts) come back.
- Visual Pun: When Scooby, Daphne and Shaggy are hypnotized, small floating stars are seeing twinkling hovering around them, which means that they are "seeing stars", a term meaning dazed.
- Water Wake Up: Scooby manages to break Daphne's hypnosis by getting an elephant to spray her with water.
- Would Hit a Girl: Zigzagged. The Ghost Clown does hypnotize Daphne, but what he has her do is far less dangerous than what he has Shaggy and Scooby do.
