He tweeted a picture of best actress winner Emma Stone moments before Beatty went on stage to announce the best picture award.
Variety also published a series of photographs taken backstage that appear to show Cullanin distracted by the activity around him.
According to Variety, Cullanin had pitched an idea to the show’s producers involving him and fellow PwC accountant Martha Ruiz “interacting” with host Jimmy Kimmel.
Cullanin is shown to have been holding two envelopes, and the assumption is that the wrong one was given to Beatty.