Deliberate mistake: When the lion appears during the beach scene, the timing doesn't add up. In the first takes it makes its way halfway out to the sand, while Jane is bathing in the ocean. After Jane is done and redresses herself, the lion suddenly emerges from the place it first appeared.
Tarzan The Ape Man (1981)
1 deliberate mistake - chronological order
Directed by: John Derek
Starring: Richard Harris, John Phillip Law, Bo Derek, Miles O'Keeffe
Continuity mistake: Near the end of the movie Jane's wearing a loin cloth like Tarzan that the natives dressed her in. When she's with Tarzan and a monkey after washing off the white paint she's suddenly wearing a skirt.