Rebecca Johnston had a hat trick as Canada’s national women’s hockey team rallied past the United States 5-3 on Saturday in an exhibition game. Jillian Saulnier and Natalie Spooner also scored for Canada in the first of two exhibitions between the powerhouses, designed to help them tune up ahead of the world championships in Plymouth, Mich., from March 31 to April 7. Shannon Szabados stopped 32-of-35 shots in 51 minutes of work in net for the Canadians.