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
1987
2024
1986
2007
1960
2002
1998
1955
2012
2003
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1994
2023
2017
2019
2013
2001
1976