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The Bonnie and Clyde actress added that she assumed it was a theatrical ploy.
"I thought he was joking. I thought he was stalling. Warren's like that, he kind of holds the power ... but it's part of his charm. I read the name of the film on the card."
Along with the audience, Dunaway claims she was "completely stunned."
"You don't know what has happened," she said. "I [felt] very guilty - I thought I could have done something, surely, why couldn't I have seen Emma Stone's name on the card?"
The two PricewaterhouseCoopers accountants in charge of handing over the winner's envelopes have since been stood down, although the Academy has announced it will continue using the accounting firm for future ceremonies.