The Challenger Explosion
On January 28, 1986, the Challenger space shuttle exploded a mere 73 seconds after lift off. All seven crew members died that day, including a teacher named Christa McAuliffe, who had joined the expedition to teach from space.
While there’s no doubt that the shuttle disaster happened, there are a couple of people who seem to remember the accident happening in 1984 or 1985. Perhaps in some parallel universe the explosion did happen in those years. But in this reality, the year of the explosion was 1986.