When Daphne invites the rest of the gang to join her and her friend Sean (aka famous actor, director, and producer Sean Astin) for lunch, she's adamant that it go well, which means no one can say the word "ring"...but then Velma spots a lost key. Declaring it a quest, Sean drags "the Alliance of the Ring...of Key" into helping him restore it to its rightful owner, which leads them into a mystery involving a plant monster.
This episode includes examples of the following tropes:
- Accidental Hero: Sean's insistence on personally returning the key ring to its rightful owner pulls the gang into another mystery, preventing the villain of the week from getting away with her scheme.
- Attack! Attack... Retreat! Retreat!: The plant monster chases Fred and Sean into a freestanding door, only to run back out again when they counterattack with a fire-extinguisher-size container of weedkiller.
- Four Eyes, Zero Soul: Subverted; the gang and Sean are watched throughout the episode by a mysterious man with creepy glasses. However, when he appears, he turns out to be a friendly bank detective independently investigating and he apologizes for the intimidating effect the glasses have on his eyes.
- Gaia's Vengeance: When Fred goes for the weed killer to fend off the monster plant, one of the salespeople chastises him and coos over the cut vines. She isn't impressed when Shaggy claims self-defense, saying that plants have been getting hurt by people for a long while and now they're striking back. When she's unmasked as the plant creature, the gang initially thinks maybe she's appointed herself an avenger of the plant world. She answers "no"; the only "green" she's interested in these days is dollar bills.
- Giving Them the Strip: When Sean grabs Scooby's collar and the back of Shaggy's shirt to prevent them from fleeing the plant monster, the two cowards simultaneously slip out of their respective garments to run away. They briefly return, but just long enough to snatch their clothes back from Sean.
- Here We Go Again!: At the end, Sean finds a pirate map and drags the gang into hunting with him.
- I Always Wanted to Say That: Given the gushing the others do about Sean's role in Lord of the Rings earlier and the huge grin on Shaggy's face as he drops one of Sam's most famous lines, it's pretty clear he's been waiting for a chance to make the reference (or maybe any reference to the trilogy).
- Ignore the Disability: Daphne warns the others not even to say the word "ring" in any context because the word is a trigger for Sean. She ends up being the first one to break that rule.
- Interclass Friendship: It's never said how they met, but Daphne is friends with celebrity Sean Astin, enough that she refers to him as just "[her] friend Sean" and tries her best to keep the gang's lunch with him normal.
- Irony: Sean insists on personally returning the lost key ring to its owner. Its owner is the plant monster, and Sean spends a good chunk of the episode keeping the key ring out of the plant monster's grip.
- Mundane Made Awesome: Even aside from the mystery and the plant monster, Sean treats finding the key ring and returning it personally to its owner as an epic quest ala The Lord of the Rings.
- Noodle Implements: Whatever trap Fred was planning, it involves a (literal) cartload of DIY supplies like nylon rope, spray primer, and chainsaws. That trap never gets built because the monster shows up too soon.
- Planimal: The monster of the week is a tall, 350-pound plant with vines for arms and legs. It also has control of a huge vine network and some hideous-faced flowers that spray victims with knockout gas.
- Puppy-Dog Eyes: Sean Astin tries to stop Shaggy and Scooby from walking away when things get spooky but is having no success...until he breaks out "the sweet, sad eyes" as Shaggy puts it.
- Running Gag: Sean continually referring to the "artifact" as "the ring...of key."
- Series Continuity Error: Daphne claims that Sean's complex over the word "ring" came about because he never got to hold the ring prop during the filming of the trilogy. That can't be possible because Sean's character, Samwise Gamgee, did in fact carry the ring, albeit briefly. note
- Shout-Out:
- Shaggy runs away from the monster with Sean Astin and Scooby (carrying the key ring) in his arms. He quips that he can't carry the key ring, but he can carry Sean and Scooby, who's carrying the key ring.
- At the end, Sean drags the gang into another mystery this time involving a pirate map.
- Trauma Button: The word "ring" causes Sean to go into a trance, even if it's said in a totally different context (e.g., "ring up the check"). When Velma finds a key ring, he insists on questing for its owner.
- We Sell Everything: The More Walls, Doors & Stuff store, though primarily a home-repair and gardening supply outlet, stocks everything from onion rings to live snakes to a hay-baling machine.
