Steve McQueen's role was originally going to be played by Sammy Davis Jr.. A feud had broken out between Davis and Frank Sinatra after Davis had claimed in a radio interview that he was a greater singer than Sinatra. Sinatra demanded he be dropped from the cast, and McQueen got the part. McQueen was mainly noted at the time for the television series Wanted: Dead or Alive (1958) and the horror movie The Blob (1958). Never So Few (1959) marked his introduction to working with director John Sturges, who went on to cast McQueen in his breakout role the following year, as second lead in The Magnificent Seven (1960), and later as the motorcycle-jumping lead in the classic The Great Escape (1963).
This movie is based on the real-life story of World War II's OSS Detachment 101. This was an OSS Operations Group designed to specialize in activities in the China-Burma-India region in collaboration with the Kachin Rangers and other Allied special operations units.
MGM producer Sol C. Siegel imposed a happy ending on John Sturges who wanted to let Frank Sinatra's character die.