The 89th annual Academy Awards were almost over Sunday night when the biggest goof-up that could possibly happen, happened.

Actors Warren Beatty and Faye Dunaway were handed the wrong envelope to read for the best picture winner, sending the cast and crew of " La La Land" onstage to make speeches before realizing the actual winner was "Moonlight."

Acceptance speeches from "La La Land" producers were still in progress when one of them, Jordan Horowitz, rushed back to the mic and announced "Moonlight" had actually won.

Horowitz had to keep insisting it wasn't a joke, but at first it seemed unclear if he was serious.

Once the mistake was clear, Beatty showed the audience the card he and Dunaway were given stated Emma Stone won for "La La Land." Stone had just netted a gold statue for best actress, and it seemed Beatty and Dunaway were handed a second copy of the best-actress envelope.

Give Beatty credit -- he seemed confused by the card he drew from the envelope, handing it to Dunaway to confirm. But expecting to see a best-picture name, she read "La La Land" as the winner.

PwC, the accounting firm that handles the Oscar voting, quickly issued an apology, saying "the presenters had mistakenly been given the wrong category envelope."

Former Oscar host Neil Patrick Harris pointed out the award name on the envelope was wrong.

And former Twitter CEO and Medium founder Ev Williams pointed out there are actually two complete sets of winner envelopes kept in different briefcases, as noted in a Medium story that displayed photos of the two briefcases.

Later, host Jimmy Kimmel jokingly took credit for the mishap, saying, "I knew I'd screw up this show."

Needless to say, the mix-up shocked viewers and social media mavens alike -- although Twitter user Lex Friedman seemed to predict it when Beatty stepped up to the mic. (But it wasn't Beatty's fault!)

The Academy itself, and some major publications, had already tweeted "La La Land" as the winner, and had to quickly delete and retweet.

And once it had settled in that the mistake wasn't a Kimmel prank, the jokes started to fly.

Many Oscar watchers couldn't help but compare the gaffe to the 2015 Miss Universe pageant, where host Steve Harvey read the wrong name and Miss Colombia was briefly crowned instead of the real winner, Miss Philippines.

Even the official Twitter account of the Miss Universe pageant offered aid.

Not everyone bought that the flub was an accident.

And, of course, who could resist an election joke?

First published Feb. 26 at 9:29 p.m. PT.

Updated at 10:10 p.m. PT and again on Feb. 27 at 5:12 a.m. PT: Added further details and reactions.

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