According to Frank Sinatra Jr. on the DVD commentary, Sammy Davis Jr. was forced to stay at a "colored only" hotel during the filming because Las Vegas would not allow blacks to stay at the major hotels despite his appearing with Frank Sinatra, Dean Martin, and the others at the Sands Hotel. He was only allowed to stay at the major hotels after Frank Sinatra confronted the casino owners on his behalf, therefore breaking Vegas' unofficial color barrier. That hotel was Mrs. Harrison's Boarding House, located in the historic Westside district. The establishment hosted a stellar array of African American entertainers in its day and is now a listed historic building.
In a scene between Danny (Frank Sinatra) and Adele (Patrice Wymore), Adele throws a dish of candy at Danny. The throwing of the dish was ad-libbed, which accounts for the genuine look of surprise on Sinatra's face and the faces of his co-stars.
Sammy Davis Jr. required wooden blocks attached to the pedals on the garbage truck he drove in the film so that he could reach them.
Significant portions of the movie interactions between major characters were ad-libbed. The actors playing the leading roles all knew each other well and improvised dialogue as good as or better than the script.
During Dean Martin's scene with Shirley MacLaine, after she calls him "Ricky Nelson", Martin replies "I used to be Ricky Nelson but now I'm Perry Como." In real life, early in his singing career, music critics used to derisively refer to Martin as a knock off of Perry Como. In addition, Martin had just done Rio Bravo (1959) co-starring Ricky Nelson.