1981 was a year in the 20th century.
- Date Unknown: George McFly bought clothes at Sears, which he still wore in 1985.
- Date Unknown: The 1982 DeLorean DMC-12 is first constructed and sold.
- Biff Tannen Jr. was born to Biff Tannen and an unknown woman.
- In 1931, the Hill Valley Science Expo featured a diorama entitled Hill Valley of the Future, which depicted life in a suitably futuristic Courthouse Square in 1981. Marty McFly wished that the town had looked that good in the actual 1981.
- Had the Hill Valley Science Expo continued, Emmett Brown (who was banned for 50 years due to his Electrokinetic levitator crashing into Atlas House of Glass) would have been permitted to return as a contestant.
Behind the scenes
- Back to the Future: The Game
- Back to the Future: The Game - Episode 4: Double Visions (First mentioned)
- Back to the Future: The Game - Episode 5: OUTATIME (Alluded to)
- BTTF novel p.28
- "Verne Hatches an Egg": Assuming Biff Jr. is about 11 in 1992, which would place his birth in 1981.