It Happened at the World's Fair (1963)

Mike and Danny fly a crop duster, but because of Danny's gambling debts, a local sheriff seizes it. Trying to earn money, they hitch-hike to the World's Fair in Seattle. While Danny tries to earn money playing poker, Mike takes care of a small girl, Sue-Lin, whose Uncle Walter has disappeared. Being a ladies' man, he also finds the time to court a young nurse, Diane.