Don Cheadle only had a couple of weeks to prepare for the role of Sammy Davis Jr.. He learned to sing, tap dance, play drums, play trumpet and twirl six-shooter pistols like Davis did. He took tap dance lessons from Savion Glover.
Ray Liotta, along with the usual preparation of watching Frank Sinatra's performances and films, also watched Nixon (1995) starring Anthony Hopkins. Liotta was inspired by Hopkins because Hopkins did not resemble Richard Nixon but convincingly portrayed him.
Don Cheadle was uncomfortable with the scenes in which Sammy Davis Jr. laughs at racial jokes made at his expense. He asked writer Kario Salem to include the scene in which Davis explains to May Britt that he endures the jokes so that future black entertainers will not have to do so.
William Petersen portrays John F. Kennedy in "The Rat Pack" and also JFK's father Joseph P. Kennedy in "The Kennedys of Massachusetts".