Michael Keaton is seen wearing a Pittsburgh Pirates hat in the movie. Keaton is from Pittsburgh, and an avid Pirates fan.
Christopher Reeve and Michael Keaton portrayed DC comic book superheroes on the big screen: Reeve played Superman in Superman (1978), Superman II (1980), Superman III (1983), and Superman IV: The Quest for Peace (1987); and Michael Keaton played Batman in Batman (1989) and Batman Returns (1992). And, in the upcoming Flash movie.
Michael Keaton turned down Batman Forever (1995)when Tim Burton left the project. He did this instead.
Inspired by the real-life relationship between James Carville and Mary Mataline. Unlike their film counterparts, Carville is a Democrat who worked for Bill Clinton's campaign, while Matalin is a conservative Republican who worked for George H.W. Bush.