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In the famous "Mouth of Truth" scene, Audrey Hepburn's reaction to Gregory Peck's "bitten-off hand" was genuine. Just before the cameras rolled, Peck quietly told director William Wyler that he was going to borrow a gag from comedian Red Skelton, and have his hand hidden up his sleeve when he pulled it out of the sculpture's mouth. Wyler agreed, but Hepburn was not told. When she saw Peck's "missing hand," she let out what she later described as "a good and proper scream." The scene was filmed in only one take.
When Gregory Peck came to Italy to shoot the movie, he was privately depressed about his recent separation and imminent divorce from his first wife, Greta Kukkonen. However, during the shoot he met and fell in love with a French-born woman named Veronique Passani, of Italian and Russian parents. Following his divorce, he married her, she became Veronique Peck, and they remained together for the rest of his life.
After filming, Gregory Peck informed the producers that, as Audrey Hepburn was certainly going to win an Oscar (for this, her first major role), they had better put her name above the title. They did and she did.
Paramount originally wanted to shoot this movie in Hollywood. William Wyler refused, insisting it must be shot on location. They finally agreed, but with a much lower budget. This meant the movie would be in black and white, not the expected Technicolor, and he would need to cast an unknown actress as the Princess, Audrey Hepburn.
Audrey Hepburn won the role of Ann thanks to a legendary screen test. She performed a scene from the film, and the cameraman was instructed to keep the cameras rolling after the director said, "Cut." Several minutes of unrehearsed, spontaneous Hepburn was captured on film. That, combined with some candid interview footage, won her the role.
Audrey Hepburn won the 1953 Best Actress Academy Award for Roman Holiday. On March 25th, 1954, she accepted the award from the much revered Academy president Jean Hersholt. After accepting the award, Audrey kissed him smack on the mouth, instead of the cheek, in her excitement. Minutes after accepting her 1953 Oscar, Audrey realized that she'd misplaced it. Turning quickly on the steps of the Center Theater in New York, she raced back to the ladies' room, retrieved the award, and was ready to pose for photographs.