Hey, It's That Voice!: The voices were provided by the members of Pittsburgh's WDVE Morning Show, leading to this trope for those in western Pennsylvania.
Of particular note: The Mayor has the same exact voice as WDVE's satirical portrayal of then-mayor Tom Murphy. So you can choose to believe that the resident Card-Carrying Villain is the mayor of Pittsburgh.
Talking to Himself: Jim Krenn, who played The Flesh, Stinky Diver, the Mayor, Bill the Lab Guy, and Hodge Podge. Also, Scott Paulsen plays Meltman and the narrator. In short, half the cast is two people.