In order to save the world from a nuclear holocaust in 2045, Doc Brown must push the technological age back at least 50 years preventing Mattel Hoverboards and Mr. Fusion from being created.
2017
2006
2014
2013
2018
1996
2021
2007
2005
1986
1998
2020
1984
2022
1999
2004
2001
1987