For his performance as Homer Parrish, Harold Russell became the only actor to win two Academy Awards for the same role. The Academy Board of Governors thought he was a long shot to win, so they gave him an honorary award "for bringing hope and courage to his fellow veterans through his appearance." Later in the ceremony, he won for Best Supporting Actor.
To avoid awkwardness when he first met his fellow cast members, Harold Russell made a point of reaching out with his hooks and taking their hands, thus putting them at ease with his disability.
When Homer is lighting everyone's cigarettes, after the second one he asks if either of the two men are superstitious. They say no and he says that he is, blows out the match and lights up a second. This is in reference to a habit amongst ground troops of the first World War. It is called the Three on a Match superstition: the enemy would see the light as the first cigarette is lit, they would take aim when the second is lit and would pull the trigger when the third is lit.
Harold Russell was discovered by William Wyler after he saw him in an army training film called Diary of a Sergeant (1945), about the rehabilitation of wounded servicemen.
Director William Wyler was furious when he learned that Samuel Goldwyn had sent Harold Russell for acting lessons: he preferred Russell's untrained, natural acting.