The first motion picture filmed in CinemaScope outside of the United States. Prior to beginning principal shooting, 20th Century-Fox studio execs warned producer Sol C. Siegel and director Jean Negulesco that they would have a difficult time with the new film format away from the controlled settings of the studio. Siegel and Negulesco solved this dilemma by simply taking the studio's entire technical crew along to Rome.
The Trevi fountain is so named because it is located at the intersection of three roads. Tre+via=three roads.
Although the movie title refers to three coins, only two coins are actually seen thrown into the fountain. The third is reportedly, thrown in by Giorgio.
After her discovery by Otto Preminger, who introduced her to film audiences in The Moon Is Blue (1953), Maggie McNamara was signed by Fox, and Three Coins in the Fountain (1954) was her first film under the new contract. Though her screen debut earned her a Best Actress Oscar nomination, McNamara's star faded quickly. This would be a pattern for the majority of leading ladies discovered by Preminger, including Jill Haworth, Jean Seberg, and Dorothy Dandridge, all of whom either committed suicide or died young.