Three cult natives are shown rising from brush to attack Captain Bishop (Murray) on the boat. Tarzan side-tackles all three and knocks them all down. Then Tarzan dispatches two of them and one is seen fleeing away. However, the next scene shows three natives on the ground.
The boat is traveling on a river in Brazil and come across a herd of hippopotamus in the river. Hippos are indigenous to Africa and therefore should not have appeared in a river in South America.