When Raspy Kelly goes to Lawrence's apartment, the entire city is in a blackout due to the storm. He uses the doorbell and intercom, even though there's no power.
During the blackout scene, Raspy and Larry are both holding cigarettes. The wind blows out a candle; simultaneously the lights come back on. At that moment, Larry's cigarette disappears.
The zombie (in a suit of armor) attacks Hope with a mace. As they wrestle in a long shot, he drops the mace, but in the next close-up, the mace is in his hand again.
When the man dies in the crypt, his eyes are open. In the next shot, his eyes are closed.
When Geoff Montgomery knocks on the door to Mary Carter's hotel room, he's wearing his hat but when she opens the door he has it in his hand even though there hasn't been sufficient time after the cut take for him to have removed it.
This film, like all the Tarzan ones and other exotic locale-type films with lush foliage or jungle scenes, makes significant use of the sound of the Kookaburra (bird), which is found only in the Southern Pacific area. The usage is intentional, for effect, and relies on the lack of education of most viewers.
Obvious wires hold up the fluttering bats.
The flashlight that Hope uses must not be battery powered. You can see him dragging a wire attached to one his shoes whenever he is using the flashlight and his feet are visible.
The caretaker of the island is lousy at her job. She asks Hope and Best what they want. Hope responds with a quip. Instead of ordering them off the island, she hides in her shack.
Lloyd Corrigan's character Martin is portrayed significantly, accidentally bumping into Mary on a number of occasions, and rescuing her from Francisco in the night club. Yet his identity and purpose are never explained.
The elevator operator tells Larry that room 1409 is "down the hall and to the left" yet he gestures down the hall and to the right.