“The choppy second act has never been a miracle of plotting. But Mr. Prince and Susan Stroman, his gifted choreographer, fill in a lot of the blanks with two pantomimed montages. The first traces Gaylord and Magnolia's ruinous days together in Chicago. The second, a dazzling 21-year flash forward in the life and customs of the country, is a virtual March of Time newsreel, sumptuously costumed by Florence Klotz.”