A baseball team will be based in Miami

Robert Zemeckis : director
In 2015, Marty sees that the Cubs beat a baseball team from Miami to win the World Series. In 1985 (when "BTTF Part II" is set) and in 1989 (when it was released), there were no baseball teams in Miami.

Back to the Future Part II, 1989. Film. Directed by Robert Zemeckis. USA: Universal Pictures