Ability over Appearance: Classic screen beauty Olivia de Havilland is of course far too gorgeous to be a character intended to be plain. But much like Melanie in Gone with the Wind, her performance sells it.
Channel Hop: With the advent of television, Paramount sold the rights to Universal Studios in 1958 for the film to be shown on the airwaves. Ever since then, The Heiress has been distributed on VHS and DVD by Universal Home Entertainment.
Montgomery Clift was so unhappy with his performance, he walked out of the Premiere.
Composer Aaron Copeland disowned the film, because his score was replaced at the last minute. Known for subtler and more transparent music, the "spareness" of the score disturbed William Wyler, who had it re-written and re-orchestrated to be more like a typical Hollywood score.
Enforced Method Acting: For the scene where Catherine realizes she's been jilted, William Wyler had Olivia de Havilland carry suitcases full of heavy books. This had her looking convincingly weary, and she actually fainted from exhaustion after the last take (which was of course the one he used).
Olivia de Havilland and Montgomery Clift didn't get on, apparently because the latter looked down on her and didn't value her talents as an actress.
Ralph Richardson likewise kept trying to undermine Olivia de Havilland by improvising excessively - in the hopes of stealing scenes from her.
Method Acting: Montgomery Clift learned how to play the piano for one particular scene.
Playing Against Type: Montgomery Clift had recently gotten fame for Red River and The Search, playing heroic good guys. He opted to do this to play against type, although the studio still softened his character.
Basil Rathbone was keen on reprising his role as Dr Sloper from the New York City production on the stage. It ultimately went to Sir Ralph Richardson, who had played it on the West End.
