For the Tony Award the fictitious Alice Barrington wins, the other four nominees are real life renowned stage actresses of the era: Julie Harris, Maureen Stapleton, Jessica Tandy and Estelle Parsons. While all four have indeed been nominated for Tony Awards in real life, only Parsons has never won.
Ann Miller's Taproom is a play on words in both the venue being a bar and that Ann Miller is known primarily as a tap dancer. The bar hostess is supposed to be a likeness of Miller herself.
The montage of New York City night life shown during the opening credits includes a theater marquee of the show Applause starring Anne Baxter, who plays Eve in All About Eve (1950) of which this movie is a spoof. Applause is a musical stage version of All About Eve, with Baxter actually assuming the lead role of Margo Channing in the the stage version following Lauren Bacall who originated the role.
While most of the character names are takes of the associated character in All About Eve (1950), the character of Marilyn is named for Marilyn Monroe instead of her "Eve" character name, Claudia Casswell.
When Mona and Mike are having sex, the white tube that Mike inhales most-likely contains amyl nitrate, more commonly referred to as poppers, which is a drug in liquid form used to provide an instant "high" to enhance the sexual experience.