MGM secretly sent a second unit crew to Tecate, Mexico to avoid the American laws about ethical treatment of animals. Animals were shot fighting each other, and lions were reportedly starved to promote vicious attacks on hyenas, monkeys and deer.
Director W.S. Van Dyke and many of the crew contracted malaria and were treated with quinine. Two fatal mishaps occurred during the African filming: a native crewman fell into the river and was eaten by a crocodile, and a native boy was killed by a charging rhino (which was captured on film and is in the movie). Other misfortunes also plagued the production, including flash floods, sunstroke, swarming locusts, and tse-tse fly and ant attacks.
Halfway through filming, MGM sent a sound crew to Africa because of the public's desire for all-talking sound pictures. However, the sound quality was so poor almost all the dialogue sequences were reshot at MGM's Culver City Studio. African natives Mutia Omoolu and Riano Tindama were brought back to Hollywood for some additional filming. When this activity caused rumors to circulate that the entire production was filmed on the back lot, MGM scrapped much of the new footage, including scenes with Marjorie Rambeau, who had replaced Olive Carey as Edith Trent.