1000000 B.C. was a year in the Pleistocene era, more commonly known as the Ice Age.
- Saturday, October 25: On May 2, 1991, Biff Tannen stole a DeLorean time machine from the Institute of Future Technology and traveled into the future to October 25, 2015. Doc Brown used a sub-ether time-tracking scanner which allowed him to pilot an 8-passenger DeLorean time machine full of time travel volunteers to bump Biff's DeLorean to bring him back. However, Biff avoided them by traveling to October 25, 1000000 B.C, followed by October 25, 64000000 B.C., before he was finally brought back to 1991.
- The Gale-Zemeckis coordinates listed "-1(10⁶) B.C.", translating to 1,000,000 B.C.