Jack Warner speaks of Harry Cohn as if he were still alive. Cohn died six years earlier, in 1958.
Discussing "Hush...Hush, Sweet Charlotte" with Jack Warner some time before he starts work on the film, Robert Aldrich describes the Warner Brothers film of "My Fair Lady" as the company's biggest box-office hit in years. This scene cannot be set later than the Spring of 1964, when "My Fair Lady" was actually still in process of being made. In fact, it opened in the US the day after "Sweet Charlotte", in December of 1964.
Although John Waters is a huge fan of William Castle, no attempt was made to make him look like Castle, who had a full head of hair, was much heavier and never wore a mustache.