ANTIQUES ROADSHOW is in San Antonio, Texas, where host Mark L. Walberg and appraiser Christopher Mitchell immerse themselves in the distinctive Texas atmosphere of the Buckhorn Saloon and Museum for a discussion of antique Colt pistols. At the Henry B. Gonzalez Convention Center, history continues to echo through the treasures brought for appraisal, including a valuable Chinese Tang Dynasty pottery horse, purchased mostly with cartons of cigarettes by the owner's G.I. husband in post-World War II Japan; an unusually large heirloom Teco vase from Terra Cotta, Illinois; and a collection of rare World Series programs, including the second one ever published - documenting the 1905 series between the winning New York Giants and the Philadelphia Athletics - estimated to be worth $12,800.