So the next time you think you can handle checking your email while driving, think back to the 2016 Oscars when La La Land was incorrectly announced as best picture instead of Moonlight. As the Hollywood Reporter explains in their new “Oral History of Oscar’s Epic Best Picture Fiasco,” it all came down to digital distraction.

Here’s the scene. Warren Beatty comes onstage with an envelope that had been given to him by Brian Cullinan, an accountant from Price Waterhouse Coopers, the accounting firm that tabulates the Oscars votes and is in charge of managing the envelopes on Oscar night. (They’ve been doing this since the Oscars started.) He and Faye Dunaway do their thing, then Warren opens the envelope, looks at it, and shows it to Faye Dunaway, who reads out “La La Land.”

Problem is, Beatty already suspected something was wrong, because the card also had Emma Stone’s name. Stone had just won the Oscar for Best Actress in La La Land.

Teni Melidonian, who runs Oscars publicity, explains what happened:

The lead actress envelope, which Leo [DiCaprio] handed to Emma Stone, came from Martha

This is Martha Ruiz, another accountant with Price Waterhouse Coopers. Leonardo DiCaprio, who had read out the award for best actress, had gotten his envelope from Martha.

so it made sense that Brian would have had the extra lead actress envelope.

Brian Cullinan and Martha Ruiz each had a set of envelopes with the winners. Why two sets? Because some announcers come out from stage left, some from stage right, and so you need envelope wranglers on each side.

The pro­tocol was that he would have it out until the winner was called, and then he would put it back in his suitcase–

This makes total sense.

–which he failed to do because he was distracted by tweeting.

In fact, Melidonian says, “my department had told PwC’s PR department that Brian was not allowed to do any social media backstage because he was very engaged with social media during the week leading up to the show.”

But, it turns out, Culling hadn’t followed the rule. In fact, he’d taken a picture of Emma Stone backstage right after she won– and right before giving Warren Beatty his envelope. But because he was tweeting, he didn’t put Emma Stone’s award envelope away– and instead gave it to Beatty.

Now, Cullinan was no novice to this event: it was his fourth time at the Oscars, so he knew what was involved, how high the stakes were, and how to do his job. For PwC, this is like the biggest night in the company’s calendar: when else does an accounting company get this kind of publicity?

We often tell ourselves that we can multitask when we’re doing something we’ve done lots of times before, and can do on automatic. But the story of the 2016 Oscars fiasco shows that even people who are good at their jobs, who’ve done it before, who are smart, and want to do a good job, can screw up when they distract themselves.

The one person who enjoyed the evening? Steve Harvey, who had announced the wrong winner at the 2015 Miss Universe pageant.

I was watching live and I probably knew what had happened before anybody else — ’cause I saw the panic-stricken look on the producer’s face. When he walked out there and snatched that card out of Warren’s hand, that’s when I knew redemption was mine. I was finally off the hook. Yeah, OK, I had to live that down: “Oh, how could he,” “That’s a bonehead,” “Nobody’s ever done that in the history of Miss Universe.” But the Oscars is the biggest night in Hollywood, and when they did it, I lit a cigar and drank a glass of scotch and celebrated. I was free! Thank you, God!…

Oh nah, the dude at Pricewaterhouse — he ain’t endured nothing. See, the mistake I made was against a country named Colombia. They have some people down there — they are in a different business — so when you get threats, you gotta take it a little bit differently.