Predictably, the actor was "rolling around laughing" when Peter Comfort, 90, assured him that he had been in "quite a lot of films" after seeking help from Google.
Pitt had invited Comfort to to consult on his latest Second World War film. Comfort, the last survivor of his regiment, had been invited to speak to Pitt in Hertfordshire, where he was filming Second World War blockbuster 'Fury', reported the Telegraph.
Pitt, who will be playing the commander of a DD Sherman tank crew, wanted to know what life was like inside the tanks.
"Pitt was very friendly and charming actually, but I didn't know who he was. I said to him, until last night I didn't have a clue who you were and then I Googled you and you've been in quite a lot of films. They all rolled about laughing when I said that," Comfort added.