MacArthur is wearing sunglasses when he is first shown. Suddenly, he is not wearing glasses, and they are not visible in his hands or on his desk.
At the part where Learoyd has swam ashore, and Capt. Fairbourne is aboard a nearby ship, each man waving to the other, the sunlight and water/wave conditions are vastly different between the two men's locations, even though they're not separated by much distance: Learoyd stands on the shore before a windy surf which reflects bright sunlight, while not too far away aboard the ship, Capt. Fairbourne is shown surrounded by a calm sea and overcast skies.
When Faibourne flies to Morotai to get Gen. MacArthur's
recognition of Learoyd as a king, Ferguson says the war in Europe has ended. In May 1945 MacArthur's headquarters was in the Philippines, and he had been a five-star general almost six months. In the film he wears four stars.
Just before Lian the Magnificent lands on the fire, his pants are clearly shown to be wet down to protect the stunt performer from being burned.
According to Learoyd's story, roughly three years have passed since he arrived among the tribe, but when he introduces his daughter to Sgt. Corbett, she is clearly five or six years old.
When the botanist is picked up by his lady friend, they get into a jeep. Not only did it have turn signals, it had a vinyl wrapped steering wheel. Neither of which is even remotely correct for 1942.
Lian the Magnificent's lips don't match his words.
According to Learoyd's narration, he kills Lian the Magnificent by striking him "in the heart," but the scene clearly shows him stabbing Lian in the lower side of his abdomen.