Tarzan's Hidden Jungle (1955)

Hunters trespass into Sukulu country, where animals are sacred, posing as photographers. Their work has the blessing of the U.N.'s Dr. Celliers, close friend of the Sukulu chief. The hunters send the animals across a river where they can be shot, and the natives throw the good doctor and his nurse into a lion pit. Tarzan ape-calls the animals to safety and rescues the medicos