The Empire Strikes Back

Professor Maxwell Grey stated that people thinking "Darth Vader said, ‘Luke, I am your father!’ in the second Star Wars movie" was just an example of getting facts wrong, rather than an example of the Mandela Effect. (PROSE: The Mandela Effect, Or Monsters on the Streets of London)

Behind the scenes

 * The film was never directly referred to as The Empire Strikes Back in any valid source.