Fitzgerald's family claimed that he was a descendant of 18th century patriot William Orr, a claim he dismissed. He was a childhood friend of James Joyce and he was briefly the roommate of playwright Sean O'Casey. He was often typecast as a thick-accented Irishman, especially after his Oscar-winning role in Going My Way? as a Catholic priest. Ironically, Fitzgerald was a Protestant.

Going My Way? was nominated for Oscars in ten categories and won in seven. The Academy of Motion Picture Arts and Sciences was dismayed at Fitzgerald's double nomination, and no doubt breathed a sigh of relief when he lost Best Actor to his costar Bing Crosby. They quickly changed the rules so no actor would be nominated in two categories for the same role ever again.

Fitzgerald, like every Oscar winner during World War II, took home a statue made of plastic due to wartime rationing. The $10 plastic statues were given out with the promise of an authentic one once the war was over. A few hours after the award ceremony, Fitzgerald was practicing his golf swing in his living room when he decapitated his plastic Oscar. Paramount bought him a new one the next day.