Back to The Future 3 Deleted Scene Could Have Ruined The Whole Franchise
This dark scene was cut out by the filmmakers at the last moment, saving the ending and the entire franchise from a huge plot hole.
Principal Strickland gave Biff so much trouble in high school that when Biff had become the most powerful man in Hill Valley in an alternate timeline, he retaliated by burning down the school and having his thugs systematically terrorize Strickland for the next decade.
So why did Strickland hate Biff so much? According to a deleted scene in Back to the Future 3, Biff's ancestor killed Strickland's grandfather in the Old West.
Strickland's grandfather was the Marshall of Hill Valley in 1885, and his worst enemy was the notorious outlaw Buford Mad Dog Tannen, who was, of course, Biff's great-grandfather.
Marshall Strickland is nowhere to be seen when Buford is arrested near the end of the movie, but there is an explanation: he is dead. In a deleted scene, Buford is on his way to a climactic duel with Marty when Strickland stops him.
Buford retaliates by shooting the Marshall in the back, leaving him to die in the arms of his young son. This scene has been preserved and you can still watch it.
The movie even left evidence of Marshall's assassination.
When his deputy apprehends a criminal, he can be heard saying "under arrest for the murder of Marshall Strickland."
The scene is not in the final cut, so no one killed the Marshall, and Tannen was arrested for a robbery.
However, the canonicity of the Strickland's murder is still disputed by fans. In the official novelization, he was killed, and this is also mentioned in the Back to the Future: The Game by Telltale Games.
Many viewers wondered why the Marshall disappeared at the end of the movie, and the cut scene provides the answer.
Strickland turns out to be a kind of Marshall Schrödinger — dead in the script, alive in the movie, but dead in both the novelization and the game.
The scene was cut because it was too dark, but when you think about it, the consequences are even worse. If Marshall had been killed after all, it is not a fact that his descendant Principal Strickland would have been born, and the gang could have taken over Hill Valley.
Strickland was killed while Buford was on his way to Marty, which means that if Marty hadn't gone back to 1885 and changed the timeline, none of this would have happened.
In other words, Marty is indirectly responsible for the death of his principal's grandfather.