Deliberate mistake: At the elephant graveyard, little Simba claws Shenzi in the face. When Mufasa saves Simba from the hyenas, the cuts are gone, a few seconds later. [This was done intentionally, I'm sure, for two reasons. The first being, Disney doesn't let fresh scars linger on the screen too long. Secondly, during that same scene when Mufasa rescues Simba & Nala, he claws Banzai in the rear. To stress the point later in the movie, that severe scar is shown too, but only briefly, it too disappears because of reason 1. Still a "mistake", but there's why.] (00:21:50)
Deliberate mistake: Rafiki is supposed to be a mandrill, but mandrills do not have tails. In the extended version DVD, there is a commentary by an animator who specifically admits that he knew that mandrills don't have tails (at least not like the length that Rafiki sports throughout the movie), but he put one on him anyway to make him more monkey-like. (00:02:40)
Deliberate mistake: When Rafiki comes to the pride rock for Simba's anointing, one minute he is walking through the assembled animals, the next he climbs onto the top of the rock from the front. Physically, even for an ape, it's impossible. It's a deliberate mistake, obviously his arrival would have been much less impressive if he had had to climb the mountain from the side in a slow but realistic way. (00:02:35)
Chosen answer: Rafiki is a bit of a msytic or a shaman; a quasi-magical character. He was able to smell Simba on the wind that we followed from one to the other.
Phixius ★