Will Vinton, the stop-motion animation whiz who brought us The California Raisins, is the principal creative force behind The Adventures of Mark Twain. A clay-model Twain, voiced by James Whitmore, sets out in a hot-air balloon to find Halley's Comet. Joining the waspish humorist on his journey are some of his favorite creations, including Tom Sawyer, Becky Thatcher and Huckleberry Finn. As the balloon ascends further into the sky, we are treated to animated dramatization of such Twain classics as "The Celebrated Jumping Frog of Calaveras County." Though brilliantly conceived and executed, Adventures of Mark Twain might have been even more effective had it been shortened by ten minutes or so.