An Affair to Remember was shot mostly in Hollywood, though there were location shoots in New York City and the South of France. When Cathleen Nesbitt's friends asked if she had enjoyed filming her scene as Cary Grant's grandmother in France, she had to inform them that the interior scenes had been done on the 20th-Century-Fox back lot.

As with many of his films, including the original Love Affair (1939), McCarey allowed his stars to improvise on camera and included many of their lines in the final film.

During filming cinematographer Milton Krasner pointed out to Grant that a lump on his forehead was making it hard to film his close-ups. The lump was the result of a childhood accident, but Grant had been habitually rubbing it for years, leading it to swell. Doctors told him it would take four to six weeks for him to recover from its removal. Instead, he took a few days off, had his wife, Betsy Drake, hypnotize him, and had the procedure performed in the doctor's office under a local anesthetic. He recovered within days with no scarring.

McCarey wanted the theme song of An Affair to Remember to set the film's romantic mood from the start. He and Wald hired Harry Warren, who had been writing songs for films since the coming of sound and had penned most of Warner Bros.' great Busby Berkeley musicals. Warren tried 25 melodies before he came up with a tune that would sound right as a piano piece played by Nesbitt, a traditional French song and a pop number. Then he handed the music over to Harold Adamson, who wrote the lyrics with McCarey's help.

Kerr and Grant sing a few bars of the theme song during the shipboard dance. Philips Records, which was releasing the film's songs, announced that they would sing the title song on the official soundtrack recording, but the album only included Vic Damone, who sang the song over the credits, and Marni Nixon, who dubbed Kerr's singing in most of the film. Kerr can only be heard in "The Tiny Scout," the song she performs with the children's chorus.

In a rare move for a Hollywood film of the '50s, the director was credited in the film's title. The official title card reads Leo McCarey's An Affair to Remember.

To help promote the film, Grant did a product endorsement, something he had tried to avoid for years. In this case, however, he was being honest. The ad was for TWA, his airline of choice.

by Frank Miller