Due to the error, for which PricewaterhouseCoopers apologised and took full responsibility, Warren Beatty was handed the wrong envelope.
Two sets of envelopes (each envelope containing the name of the winner of one award) are produced for the Oscars ceremony, and the two sets are held at opposite ends of the stage. The envelope that was handed to Warren Beatty was the duplicate envelope for the previous award – Best Actress in a Leading Role, which had gone to Emma Stone for La La Land. On opening the envelope, Beatty looked puzzled and showed the card to Dunaway for (one assumes) support and confirmation that something was wrong; but Dunaway, on seeing the title of a film, read it out.
By the time the error was noticed, more than two minutes later, Fred Berger and Jordan Horowitz – the producers of La La Land – were already making their acceptance speeches. After being notified by members of the Oscar crew (as Wikipedia refers to them), it was Horowitz that "stepped to the microphone, announced the error, stated that Moonlight had actually won the award, and took the card bearing the film's title from Beatty's hand and showed it to the camera and the audience as proof."
In expressing its "deep regret" over the incident, PricewaterhouseCoopers said "We appreciate the grace with which the nominees, the Academy, ABC, and Jimmy Kimmel handled the situation."
© Haydn Thompson 2021