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.
1999
2022
2016
2004
1988
2009
1989
2024
2008
2001
2021
2007
1984
2018
1960
1945
2017
1965
2019
1985