Improvised Scene: Sumner is leaving Bunny's apartment, shortly after Mike leaves and Peg arrives, when Bunny and Sumner are recapping the afternoon's events for Peg. Tracy goes "offstage" and returns with his hat pulled down over his ears, his shirt dangling out of his pants, staggering as though drunk and talking crazy. This moment, including the women's hysterical laughter and Hepburn's literally falling out of her chair, is not in the script.
Katharine Hepburn was very impressed with the performance of young Lee Remick in A Face in the Crowd (1957) and invited her to her home with Spencer Tracy to discuss appearing in "Desk Set." Tracy did not feel that the role was good enough for the young actress, however, and Remick declined it, which was then given to Dina Merrill. Tracy's advice later proved correct, as Merrill received little attention in the role.
Adapted from a Broadway play "The Desk Set" that originally starred Shirley Booth, Byron Sanders and Frank Milan. The stage production opened at the Broadhurst Theatre in New York on Oct. 24, 1955 and ran for 296 performances. "Hollywood Reporter" reported that Booth would repeat her role in the film, which ultimately did not happen (though Harry Ellerbe reprised office gossip Smithers).
Inside joke: In one scene, Bunny Watson gives Richard Sumner a striped scarf, saying it shows his college colors. The scarf's colors (red and light blue) are the colors of Ripon, the college Spencer Tracy attended in real life, not MIT, the college that Sumner is said to have graduated from in the movie.