It happens frequently these days that release dates gets outed at various online retailers. IGN reported an image of a "pre-order" card at Best Buy putting the Mafia III release date on April 26. Online retailers GameStop and Amazon also had the same date for a while on their game pages. Each on its own could be put down as a mistake, but clearly with all three using the same date it is either a case of a place holder date being communicated centrally from 2K Games or it is actually the real release date. A bit sooner than we were expecting if it is indeed the case.
2K Games provided IGN with a standard boiler plate answer that either implies the date slipped prematurely or that it is wrong.
"Mafia III will release in calendar 2016 during Take-Two Interactive's fiscal year 2017. No official release date has been announced at this time. It is common practice for retailers to list placeholder dates before an official release date has been announced due to the requirements of their operating systems."