DiCaprio stars as controversial Federal Bureau of Investigation (FBI) boss J. Edgar Hoover in the upcoming drama, while Hammer plays lawyer-turned-FBI agent Clyde Tolson, his rumoured lover.
But it was the Titanic star who came under interrogation on-set after Hammer's wife, former model Elizabeth Chambers, demanded to know if DiCaprio remembered a friend of hers he once bedded in his Lothario heyday.
Chambers recalls, ""I actually met Leo when I was modeling in Tokyo when I was in high school. He hooked up with my roommate.
""When I saw him on set after all those years, I said, 'Tell me you're not an a**hole. Do not make me hate you for the rest of the shoot. She was Spanish - you took a bath your first night together. What's her name?' And he goes, 'Marta.'""