Dame Elizabeth Taylor and her husband, Mike Todd, had planned for Un gato sobre el tejado caliente (1958) to be her final movie, as she intended to retire from the screen. Todd had made a verbal agreement about this with MGM, but after his death, MGM forced Taylor to make this movie in order to fulfill the terms of her studio contract. As a result, Taylor refused to speak to director Daniel Mann for the entire production and hated this movie.
Prior to the advent of digital technology, telephone exchanges were named instead of being numbered. Thus, BUtterfield 8 (BU8 or 288) was the name of the exchange that provided service to ritzy precincts of Manhattan's Upper East Side.
Before Dame Elizabeth Taylor could start Cleopatra (1963) for a $1 million salary, she was legally bound to finish her MGM contract by doing this movie, which she hated, for her standard $125,000 salary.
Gloria's little red car is a 1960 Sunbeam Alpine Series 1.
Dame Elizabeth Taylor stated many times over the years that she disliked this movie and felt she won the Oscar because of her recent illness, rather than for the quality of her performance.