Making this movie was the first time Ingrid Bergman had been on a Hollywood sound stage since the 1940s--all her subsequent films up to that point had been made in Europe, even those for American studios.
In the record store, a customer approaches Toni and asks her a question. The album he is holding happens to be the original cast recording of the musical "Mame" starring Angela Lansbury. This is an homage to the film's director Gene Saks, since he also directed "Mame" when it opened on Broadway in 1966.
The play had been a comeback vehicle for Lauren Bacall following several years of inactivity once screen roles dried up. "Cactus Flower" was an enormous hit on Broadway, and Bacall garnered strong personal notices for her performance as Stephanie, playing the role for nearly two years. She was understandably disappointed when producer Mike Frankovich cast Ingrid Bergman in the film version.
The same plot was used years later in the film "Just Go With It," starring Adam Sandler and Jennifer Anniston. Insted of being a dentist, Sandler plays a plastic surgeon. Goldie Hawn's role is played by Brooklyn Decker.
Late in the film, when Walter Matthau and Ingrid Bergman enter the dentist office building from opposite sides, Matthau enters at 730 Fifth Avenue, the Crown Building. He is directly across the street from Tiffany & Co, where Audrey Hepburn had her Breakfast at Tiffany's. Jack Weston appeared with Audrey Hepburn two years before Cactus Flower in Hepburn's Wait Until Dark (1967)
The role of Julian Winston was originated on Broadway by Barry Nelson, who was renowned in theater circles for his uncanny ability to 'freeze' a performance following a show's opening and play it exactly the same, beat for beat, for the duration of the run. This was especially evident when he was cast in a comedy, as he was able to garner laughs in the same places, performance after performance, even when the vehicle ran several years, as was the case with "Cactus Flower."
Among the LP covers adorning the walls of the record store where Toni works are movie soundtrack albums from Cat Ballou (1965), The Trouble With Angels (1966), Murderers' Row (1966), The Happening (1967), Head (1968) and Otley (1969), all produced by Columbia Pictures, which also financed and distributed Cactus Flower (1969).
When discussing the night out Igor says "I thought we were discussing my play!" To which Toni replies snarkily "I'll wait for the movie". The lines delivery implies a reference to the fact that Cactus Flower was a successful play before becoming Goldie Hawn's Oscar vehicle.