Revealing mistake: When Nala tells Simba that she is taking her bath, Sarabi (Simba's mother) tells him "And it's time for yours," and picks him up in her mouth. Her head was animated but not her body (which remains in a sitting position) so her neck appears to stretch a few feet to reach Simba.
Revealing mistake: In the scene where Mufasa and Simba are at the very top of Pride Rock and Mufasa is explaining the kingdom to Simba, one of the hand written sequence markers on the gel print is not removed. In the shot that zooms in on Simba just after the camera pans around them, there are two frames where the number 45 appear just to the left of Simba's tail.
Revealing mistake: One shot before Simba and Nala exchange lines on either side of Zazu during "I Just Can't Wait to Be King", Simba leaps to the opposite edge of a small pool of water. But notice how Zazu has been animated with a completely translucent reflection and, here, we can see the image of Simba right through him, which shouldn't happen.