Back to the Future 4' Already Happened in an Alternate Timeline

Back to the Future Part IV: Back in Timeline (Short 2015) - IMDb

Back to the Future Part II (1989) - IMDb

Marty McFly - Wikipedia

Back to the Future 4' Already Happened in an Alternate Timeline

For All Mankind' Launches a Mission to Mars, With New Wrinkles - The New York Times

Back to the Future (1985) - IMDb

Back to the Future' Series Takes Place in an Alternate Timeline - Inside the Magic

Evil doppelgängers, alternate timelines and infinite possibilities: the physics of the multiverse explained - BBC Science Focus Magazine

Back to the Future 4' Already Happened in an Alternate Timeline

The Marvels' post-credits scene, explained - Vox

time travel - Where is Marty from the alternate timeline Where George McFly is an author that Marty makes at the end of Part 1? - Science Fiction & Fantasy Stack Exchange