In basketball, an official or a referee is a person who has the responsibility to enforce the rules and maintain the order of the game. His job starts before the game starts and continues till the game ends. But referees commit mistakes, too.
They're humans, they also miss things. Remember their job is to be on the court with fastest and physically toughest athletes alive running at each other at mind-blowing speeds, of course they will sometimes slip up, too.
Let's watch some instances where the refs made the worst late game calls in the NBA.(courtesy: youtube/HoopsTube)