Back to the Future 2 does not mention disgraced DJ and TV presenter Jimmy Saville as a living human being. Jimmy Saville died in 2011.
The people of 2015 in the movie are shown to be using a synovial hinge joint between their forearm and upper arm. The real, non-movie people of 2015 do indeed have these joints - called elbows - which are as popular today as they were in the film.
There is no mention in Back to the Future 2 of my uncle Terry having gotten off his fat arse and landed a job. In fact, my uncle Terry still hasn’t gotten off his fat arse and landed a job, much to Aunt Carol’s despair.
The fictional world of 2015 is not one where the Brine People have emerged from the Salty Wastelands and enslaved humanity. The actual world of 2015 still awaits the Brine People’s wrath.