April 18 is the 106th day of the year.
- 1906, Wednesday: San Francisco, California had an earthquake.
- The Hill Valley Courthouse was used as a shelter for the victims of this earthquake.
- 1938, Monday: The first issue of Action Comics (Known mostly for the introduction of Superman) is made available for purchase.
- Back to the Future: The Game
- Back to the Future: The Game - Episode 3: Citizen Brown (Mentioned on the Self Tour speaker by the Courthouse.)
- Back to the Future: Untold Tales and Alternate Timelines 4