"Mona Lisa" was the first song not performed in English to win an Oscar for Best Song. Amazingly, it was more than fifty years before another foreign language composition took the gold. As of 2020, only two songs have accomplished the feat: "Al Otro Lado Del Rio" from The Motorcycle Diaries (2004) and "Jai Ho" from Slumdog Millionaire (2008).
Although set in post-war Italy and featuring an important local Italian family, none of the 5 featured actors is Italian. Joseph Calleia (Dr. Lunati) is Maltese; Richard Avonde (Carlo) is Canadian, Celia Lovsky (Contessa) and Francis Lederer (Baron Rocco) were born in what was Austria-Hungary; and Wanda Hendrix (Baronessa Giulia) is from Jacksonville, FL.
Composer Hugo Friedhofer subtlely weaves the opening notes of "Mona Lisa" into his background score, but the song does not appear in the main title or end credits of the film and is never sung in English. Its only presentation is in the wartime sequence at the film's start, informally warbled in Italian by a soldier standing guard while accompanying himself on guitar, purely as a covert means of warning his fellow soldiers that danger is imminent.
There had been numerous Best Song nominations from non-musical pictures since the advent of the category in 1934, but "Mona Lisa" was the first of these to actually win the Academy Award. Captain Carey, U.S.A. (1950) did not hold the distinction for long. In fact, it broke the lock musicals had had on the category until that time. Just two years later, High Noon (1952) repeated the feat, quickly followed by Three Coins in the Fountain (1954), Love is a Many-Splendored Thing (1955), The Man Who Knew Too Much (1956), The Joker is Wild (1957) and A Hole in the Head (1959). By the 1960s, with musicals now out of vogue, it became commonplace for a drama or comedy to win Best Song, with only two statuettes going to musicals: Mary Poppins (1964) and Doctor Dolittle (1967). In the decades that followed, only five musicals scored gold: Nashville (1975), A Star is Born (1976), Thank God It's Friday (1978), Fame (1980) and Flashdance (1983). Not until Disney returned to making animated features in 1989 did musicals once again become serious contenders for a Best Song Oscar.
For decades, confusion has surrounded the film's Oscar win for Best Song, as the official release year was 1949, while the statuette was bestowed for the year 1950. In an unusual twist for a Hollywood product, Captain Carey, U.S.A. (1950) premiered in London in late 1949, not opening in the U.S. until the turn of the year, in February 1950. As such, its American premiere date dictated its Oscar eligibility for the year 1950.