How an Oscars rule led to this year's massive best picture screw-up

Warren Beatty was mistakenly given the wrong envelope to announce the best picture winner at Sunday's Academy Awards, in a moment that will go down as not just the biggest Oscar screw-ups, but one of the biggest awards snafus ever.

But after the madness of trying to sort out that it was "Moonlight" that actually won best picture, not "La La Land," the big question around all the after-parties was how could Beatty and fellow presenter Faye Dunaway have been given the envelope for best lead actress, which went to Emma Stone, as that award had already been given out?

Beatty said onstage that the card he was given said Emma Stone. And screenshots from the telecast prove that he's right, as this tweet shows:

But to thicken the plot even more, Stone told the press room after the madness that she was holding onto the best actress envelope while onstage with the "La La Land" cast and producers when they thought they won.

It turns out, PricewaterhouseCoopers, the accounting firm in charge of vote counting for the Oscars, show up on Oscar night with two sets of winning envelopes. Employees of the firm stand on opposite sides of the stage and are in charge of handing the sealed envelopes to the presenters before they go out to name the winner.

So it seems Leonardo DiCaprio, who presented the Oscar to Stone for best actress, walked onstage from a different side than Beatty and Dunaway did, leading to the duplicate being used.

Why the need for duplicates? In an interview with MarketWatch before the Oscars, Brian Cullinan, one of the PwC accountants in charge of Sunday's winning envelopes, said it's largely to make sure Los Angeles traffic doesn't play a factor in getting the envelopes to the ceremony.

"We have two briefcases, that are identical, and we have two entire sets of winning envelopes. [Fellow accountant] Martha [L. Ruiz] carries one of those briefcases, I carry the other. We go to the show separately with police escorts. I used to think it was for our security, it's really for the briefcase. [Laughs] We take different routes to get there just because of the kinds of things that can happen in L.A. traffic. We want to make sure that no matter what happens, one of us gets there. We've never really had a problem with that." 

You better believe there's going to be some tweaking done to the process.

But there are still unanswered questions, like why didn't the PwC accountants act quicker to fix the error once "La La Land" was incorrectly named the winner? It was a good couple of minutes before "La La Land" producer Jordan Horowitz stopped everything and revealed the winning best picture card that read "Moonlight."

Deadline is reporting that one of the accountants told a stage manager about the error, and that person then went onstage with the correct card. 

PwC issued a statement late last night saying that it is "currently investigating how this could have happened."