After being jailed for solving a mystery, the gang stumbles upon yet another case: a slime mutant that lives underneath Crystal Cove is cocooning anyone who gets in its way. Despite being warned not to continue investigating by their parents and authority figures the gang attempt to solve the mystery anyway.
It's high fives all around as the gang have just solved another mystery. They plan on celebrating, but they aren't going anywhere, as Sheriff Stone locks them in a jail cell for not only interfering, but because they're upstaging him. He tells them he's going to call all their parents, whom he now has on speed dial, especially Fred's, the mayor's son.
None of the people in Velma's tour group are actually tourists. Either they all decided to move there afterwards or they all just happened to be new in town. It's also possible that they had just never taken it before. However, the two that talk are credited as tourists.
Before walking into Fruitmeir's, Daphne's carrying a handbag around her arm which presumably contains Shaggy and Scooby's belongings, then when she enters, her handbag is gone and she's just holding said belongings.
There's clearly something dodgy going on, as Franklin doesn't even know what his own dessert is made of, and the large storage room in the back of Fruitmeir's contains six barrels with radiation symbols on them, and many more smaller containers with that symbol.
Daphne: Just once it would be nice if someone thanked us for solving a mystery. Fred: Good thing we're not in this to be liked.
(the gang give him funny looks) Fred: Maybe that didn't come out quite right.