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 well as or better than the script.
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.
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.
As Peter Lawford, Dean Martin and Frank Sinatra attempt to disguise themselves by blackening their faces in the garbage truck near the end of the movie, Sammy Davis Jr. says, "I knew this color would come in handy some day." Martin and Sinatra teased Davis about that scene for as long as they knew each other thereafter.
In the theatrical trailer, the announcer states "Danny Ocean is holding his own summit". This is a possible joke reference to the legendary Rat Pack shows at the Sands which took place during filming. The shows were known as "The Summit".
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.
In the final shot of the film, the eleven walk past the famous sign in front of the Sands hotel. The five members of the Rat Pack (Frank Sinatra, Dean Martin, Sammy Davis Jr., Joey Bishop, and Peter Lawford) are billed on the sign. They were performing alternately in the hotel's Copa Room during production, at the "Summit at the Sands".
KLAS TV reporting in the wake of the heist was a real Las Vegas media station. Not long after this movie was released, Vegas millionaire resident Howard Hughes bought it so he could control what movies aired on late night television.
Most filming was accomplished early in the morning, before sunrise, since most of the actors also had shows in Las Vegas that they performed nightly during the shooting. The actors would wake up in the afternoon, do one or two shows in the evening, then go through make-up and arrive at the shooting locations for principal photography. Each shooting location was fully set up in advance so that minimal time would be wasted once the actors arrived.
Shirley MacLaine's tipsy uncredited cameo was ad-libbed by the actress, for which she reportedly received a brand new car from Warner Bros. as compensation. Her line, "I'm so drunk I don't think I could lie down without holding on," was a rehash of a classic Dean Martin line.
Right after the heist when Sheriff Wimmer is interrogating a possible witness over the phone, the uncredited voice on the other end of the line is that of George Fenneman, better known as the announcer on such TV game shows as You Bet Your Life (1950) and Tell It to Groucho (1962).
Shirley MacLaine shot her quick cameo during a break in filming The Apartment (1960). Although she was offered a car for her work, she says she took the job as an excuse to hang out with her Rat Pack friends and see their Vegas show.
Major Taylor, the head of the boys military academy, is based on Donald L. Nichols, head of the Palo Alto Military Academy. Nichols was known as 'The Major' from his service with the California National Guard.
The trivia items below may give away important plot points.
The entire Ocean's Eleven does not all appear at the end as previously stated, since they were leaving Tony Bergdorf's (Richard Conte) funeral who was one of the eleven. There are however at least two scenes with all of the group together, at Spyros Acebos (Akim Tamiroff) house and at the Bowling Alley.
According to Frank Sinatra Jr. in the DVD Commentary, Danny Ocean and his men made it out of Las Vegas with the money by getting away on a chartered plane (flown by one of the Eleven). But then the entire gang is killed in a plane crash. No one liked that ending as they felt it was too much of a downer so it was rewritten to the ending shown in the movie with the money being burned up along with Tony Bergdoff's body in cremation. The idea for the cremation ending came from director Lewis Milestone, who had recently attended the cremation funeral of a friend.