From The Grindhouse Cinema Database
- Joan Crawford was early on the set every day in order to personally make breakfast for some of the crew members.
- Joan Crawford was asked by producer Herman Cohen to not drink alcohol during filming. She informed Cohen that she was "just a sipper", however she respected his wishes.
- Joan Crawford supplied her own wardrobe for the film, with the exception of the leotard which was designed by Edith Head.
- Joan Crawford changed some of the dialogue in the script saying it was too British. For example changing the word solicitor to attorney.
- Sharp eyes will notice that as Superintendent Brooks is talking to Commissioner Dalby after one of the mysterious deaths, they pass an ad that says "Come Alive! With Pepsi". Joan Crawford was the widow of Alfred Steele, who had been CEO of the Pepsi-Cola Company, and at the time of filming, Crawford was still on the Board of Directors. Product placement of Pepsi can be seen in at least one other Crawford film of this era, Strait-Jacket (1964).
- Two performers dressed as Batman and Robin appear in the circus, at the beginning of the London premiere, with all of the other circus performers. Michael Gough, who played Albert Dorando in this film, played Alfred the butler in the 1989-1997 series of Batman films.
- This film marked the second time that Diana Dors played a carnival performer who ends up cut in half by a power saw. The first time occurred in 1962, in "The Sorcerer's Apprentice" episode of Alfred Hitchcock Presents (1955).
- George Nader, rather than Ty Hardin, was reportedly the first choice to play the part of "Frank Hawkins."