1984 was a year in the 20th century.
- June - Linda McFly graduated from Hill Valley High School with the Class of 1984, according to the sweatshirt she wore in the photograph in Marty's wallet.
- Tuesday, November 6 - Ronald Reagan was elected to a second four-year term as President of the United States.
- (Date unknown) - Nintendo released the light gun video game Wild Gunman into arcades in an updated format, replacing the still photographs of the original 1974 release with cartoon-style sprite graphics.
- (Date unknown): In the 1986A timeline, Marty left Hill Valley under the condition that the Tannen Crime Family left Lorraine and George McFly alone.
Behind the scenes
- July - The third draft screenplay of Back to the Future was finalized.
- Friday, October 12 - The fourth draft screenplay of Back to the Future was finalized.
- Monday, November 26 - Production of Back to the Future began, with Eric Stoltz in the role of Marty McFly for the first four weeks of filming.
- Thursday, January 5: The Family Ties episode "Birthday Boy" airs. The episode guest stars Crispin Glover as Doug, who is a friend of series regular, Alex Keaton (played by Michael J. Fox).
- Back to the Future (First mentioned)
- Back to the Future: The Game
- Back to the Future: The Game - Episode 2: Get Tannen! (Mentioned only)