On July 18, 2011 — Luis Mendoza of the Omaha Royals seemingly throws a no-hitter against the Memphis Redbirds. However, right after the game ends, the official scorer changes a 9th-inning error by Omaha LF David Lough into a hit for Tyler Greene, taking the no-hitter away. An hour later, he changes his mind again, returning the no-hitter. Two days later, the Pacific Coast League will decide that it was in fact a hit for Greene, again costing Mendoza the no-hitter.
Source:
Baseball Reference July 18