just a idea for a very small DLC, 
you find a Playstation 4 in the backseat of the Dolorean connected to a small TV, turned on & in rest mode, obviously it’s disconnected from the Internet because its 1989, apparently Marty Mcfly was playing one if the events generation zero has & just left it in rest mode so he can play events anytime, & collecting these PS4 left in rest mode will allow access to play events anytime