Opening sequence caves are the Bronson Caves in Griffith Park just outside of Los Angeles. These have been a popular filming location since the 1920s.
Only instance where two members of the famous "Rat Pack", Sammy Davis, Jr. and Peter Lawford, play adversaries. Every other instance in movies or television, members of the "Rat Pack" are friends. (Dean Martin; Frank Sinatra; Sammy Davis, Jr.; Joey Bishop; Peter Lawford; and honorary member Angie Dickinson).
Lawford was kicked out the Rat Pack in 1962 because his brother-in-law, then President John F. Kennedy refused to meet with Sinatra due to his alleged ties with organized crime. Sinatra blamed Lawford for this mishap.