Revealing mistake: When the prisoners commandeer the balloon and proceed to take flight, you can see a television antenna on one of the buildings in the background. (00:07:20 - 00:08:00)
Revealing mistake: When the castaways discover two women and a man washed up on the beach, they quickly determine that the women are still alive. The journalist, Gideon Spilitt, checks the pulse of the male and pronounces him dead; but the dead man's limp left hand very noticeably and unnaturally jerks twice just as Spilitt releases his wrist. The actor playing the dead man obviously had an anticipatory reflex action, but they chose to keep the shot in the film, anyway.