Director William Wyler shot 37 takes of Olivia de Havilland carrying her suitcases up the stairs. Only after the final shoot, whereupon she briefly stopped on the second flight of stairs and leaned on the handrail for a couple of seconds, did Wyler declare that this was the take he wanted to print.
After seeing "The Heiress" on Broadway, Olivia de Havilland approached William Wyler about directing her in a screen adaptation of the play. He agreed and encouraged Paramount Pictures executives to purchase the rights from the playwrights (Ruth and Augustus Goetz) for $250,000 and offer them $10,000 per week to write the screenplay. The couple were asked to make Morris less of a villain than he was in their play and the original novel in deference to the studio's desire to capitalize on Montgomery Clift's reputation as a romantic leading man.
The song sung by Montgomery Clift while playing the piano is originally a vocal romance, "Plaisir d'amour", composed in 1784 by classical composer Jean-Paul-Égide Martini, and was the basis for Elvis Presley's hit "I Can't Help Falling In Love With You" written for the movie Blue Hawaii (1961).
Olivia de Havilland wisely chose William Wyler as her director, considering that such a meticulous director would be able to coax a strong performance from her. As it turned out, Wyler became a staunch supporter of his leading actress, particularly in regard to the sneering attitude that Montgomery Clift displayed toward her (He didn't value her talents as an actress.) and Sir Ralph Richardson taking every opportunity to steal scenes from under her nose with his improvisations.