Barry Jenkins and the cast of Moonlight after winning the Oscar for Best Picture. [Photo/Agencies]

Under a tried and tested PwC procedure, just two accountants know the names of the 24 winners after their names are placed in two sets of sealed envelopes. The two accountants also memorize the winning names.

Tradition has it that the envelopes are taken separately in two briefcases to the Academy Awards venue. The two accountants- in this case Brian Cullinan and Martha Ruiz - are driven there separately in case an accident or traffic should befall them.

The pair then stand off stage at opposite sides and hand envelopes to the respective presenters as each category is announced.

Last week, Cullinan told the Huffington Post that the procedure for dealing with the hand-off of an incorrect envelope, other than signaling to a stage manager, was unclear.

"It's so unlikely," Cullinan told the Huffington Post.

Anthony Sabino, a law professor at St John's University in New York, said that although precious minutes passed, the error was corrected quickly.

"It's not as if we woke up this morning, or if it had been uncovered after the telecast was over. That would have really have been a black eye," Sabino said.

Sabino said that compared to accounting fraud at other companies in the past, "this incident diminished vastly to a vanishing point."

The Moonlight filmmakers were gracious about the error.

Director Barry Jenkins told reporters back stage that he was given no immediate explanation for the mix-up but that "it made a very special feeling even more special, but not in the way I expected."

"Please write this down: The folks from La La Land were so gracious," Jenkins added.

Reuters