

The Back to the Future multiverse proves time travel, and specifically meddling in your own timeline, has many consequences. But a deleted scene available on the Back to the Future Part II DVD reveals what was happening to Old Biff after his time travel trip. Old Biff's behavior when exiting the time machine is never explained and the films don't return to 2015.

The head of his cane breaks off in the car, which Doc finds later. The last time Old Biff is seen in Back to the Future Part II, he lands the DeLorean in 2015 and stumbles out of the car, sweating and groaning in pain, as though sick or injured.

Related: Is Eric Stoltz Still In Back To The Future?! Theory Explained This creates an alternate Back to the Future timeline, in which Marty and Doc end up, where 1985 Hill Valley is run by a rich Biff, who killed Marty's father and married his mother. He goes back to 1955 and gives his younger self the almanac. After Doc convinces Marty not to do this, "Old" Biff instead grabs the almanac and steals the DeLorean. He overhears Marty's plan to use a 2015 sports almanac to make money in the '80s. When Marty and Doc travel to the far future of 2015 in Back to the Future Part II, they meet a bitter 78-year-old Biff. In 1955, he's a high school bully who makes fun of George and harasses Marty's mother, Lorraine. In Back to the Future, Biff is introduced in 1985 as a middle-aged man who pushes around Marty's father, George.
