Back To The Future 2 Completely Reshot The Ending Of The First Movie
Wanting to have Back to the Future Part II pick up right where the first movie left off required the ending of Back to the Future to be completely reshot. The 1985 time-travel movie about teenager Marty McFly (Michael J. Fox) and absent-minded inventor Doc Brown (Christopher Lloyd) was a huge success, becoming one of the highest grossing movies of the 80s. It wasn't, however, intended to be the first part of a franchise, meaning it took until 1989 for Back to the Future Part 2 to hit theaters.
The original movie ends with Marty and his girlfriend Jennifer (played by Claudia Wells) leaving with Doc Brown in his now-flying DeLorean to head to the future to deal with an undisclosed problem pertaining to their kids. This left director Robert Zemeckis and his co-writer Bob Gale with few options about how to begin Back to the Future 2, forcing them to continue the story instead of starting a new adventure altogether. They worked out a plot that took them from 1985 to 2015 to an alternate 1985 and back to 1955 to set some time paradoxes straight, but it took a few years between writing the film, building sets, and Zemeckis' work on Who Framed Roger Rabbit before filming could start, which left the production in a familiar situation: casting issues.
Back to the Future had its fair share of casting issues when Eric Stoltz was replaced as Marty McFly by Michael J. Fox. When it came time for the sequel, Crispin Glover was recast due to contract disputes, replaced as Marty's father, George, by Jeffrey Weissman. Unfortunately, he wasn't the only cast member who wasn't able to return. Claudia Wells' mother became ill, leading to Elisabeth Shue taking over as Jennifer, which became a problem for the opening scene of Back to the Future Part 2.
Having the sequel begin with the last scene of Back to the Future required the filmmakers to start over as Jennifer was a prominent part of the original movie's ending. This involved a shot for shot recreation of Jennifer and Marty's reunion following his trip through time, now with Elisabeth Shue, and Doc's arrival, showing upgrades to the DeLorean and telling them they needed to go back to the future. The scenes line up incredibly well, too, with the most notable changes outside of the casting being some aging on Fox and Lloyd's parts and the inclusion of Biff Tannen (Thomas F. Wilson) witnessing the DeLorean taking off in the Back to the Future Part 2 version, setting up elements of the movie to come.
While it required some careful planning to make it all work, it was the smartest approach to the unfortunate situation. Trying to put Doc and Marty on a new adventure that didn't immediately follow the first film would have brought up too many questions. By reshooting this sequence and including the sense of urgency and adventure, Back to the Future Part II immediately pulls the audience right back into the world, feeling like little to no time has passed between movies.