The first time Mike Nelson dives to rescue Tom Marzack without tanks (only a mask and fins) they cut in a shot of him with tanks and the air hose in his mouth.
Anthony Caruso has broad shoulders and a very hairy chest, yet his underwater stunt double is thin with a hairless chest.
In one scene, Tom is trapped below the water when his air live gets pinned under a rock. Mike dives in the water without his air tanks to rescue him. However, an underwater close up of Lloyd Bridges shows him with his tanks and air hose.
Mr. Nelson states that there are alligators in Brazil. Alligators are endemic only to China and the United States of America.