I first saw this film on the tv’s late late show of old movies in the 1970s and then again on television on what was one of very first dates in college with  my husband of 25 years.  It was black and white movie about a small group becoming stranded on a island. Somehow a small number can be rescued as the group realizes the cannibals are closing in.  An older couple and the anti hero (who I think was Peter Lorrie) are left behind with a gun with two bullets. The closing scene is the sound of two gun fire shots as the cannibals move in as the other group is rescued to safety. Thanks!!!