The entire fiasco was the handy work of a top PricewaterhouseCoopers executive. Brian Cullinan handed the wrong envelope to Warren Beatty. He is the Chairman of PwC’s US Board and is also a Managing Partner in the accounting firm.

In what is being termed one of the most embarrassing and unprecedented mix-ups in the history of Oscars, the biggest award of the night - Best Picture - was handed over to the wrong film. It has now been revealed that the entire fiasco was the handy work of a top PricewaterhouseCoopers executive.
According to a report in The Wall Street Journal, it was PricewaterhouseCoopers U.S. board chair Brian Cullinan, who handed the wrong envelope to Warren Beatty. It has now also come to light that moments before handing over the wrong envelope, Cullinan had tweeted a photo of 'La La Land' actress Emma Stone.
He later deleted the tweet.

PricewaterhouseCoopers, the accounting firm that counts the Oscar ballots, later issued an apology on behalf of its senior executive, who is also a partner in the company.
We sincerely apologize to Moonlight, La La Land, Warren Beatty, Faye Dunaway, and Oscar viewers for the error that was made during the award announcement for Best Picture. The presenters had mistakenly been given the wrong category envelope and when discovered, was immediately corrected. We are currently investigating how this could have happened, and deeply regret that this occurred.We appreciate the grace with which the nominees, the Academy, ABC, and Jimmy Kimmel handled the situation.

Tim Ryan, the accounting firm’s U.S. chairman and senior partner, on Monday issued another statement:
PwC takes full responsibility for the series of mistakes and breaches of established protocols during last night’s Oscars. PwC Partner Brian Cullinan mistakenly handed the back-up envelope for Actress in a Leading Role instead of the envelope for Best Picture to presenters Warren Beatty and Faye Dunaway. Once the error occurred, protocols for correcting it were not followed through quickly enough by Mr. Cullinan or his partner.
