The community theatre is mounting ''A Christmas Carol,'' and all of the town's citizens are either planning to attend or be involved in the production: Barney Rubble is playing Bob Cratchit, with Betty Rubble as Mrs. Cragit and his son Bamm-Bamm Rubble as Tiny Tim; Mr. Slate is Jacob Marley; Wilma Flintstone is serving as the stage manager, while her daughter Pebbles Flintstone plays Martha Cragit; even Dino has a role, playing the Cragit's family pet.