The rest of the gang plays no part in solving the mystery; they just drop Velma off.
Inconsistencies/continuity errors and/or oddities
The reveal panel shows Missy wearing a bracelet that conceals a remote control for the monster. This was supposed to be a clue for the solve-it-yourself mystery. The bracelet is not depicted in the rest of the story.
"The Phantom of the Rock Club" is the only clunker in the box. It's quite possible that a communication problem developed between writer and artist, but the words do not gel with the art. At one point Velma refers to the Phantom as a "puppet," but puppets aren't diaphanous, nor do they get sucked through air vents, and Velma relies on a piece of evidence unseen until the final reveal. The evidence should have been present throughout.