Continuity mistake: When the evil king's female assistant is "turned into" Odette, and Prince Derek is dancing with her near the end, he puts the locket on her. The chain goes around her hair, and in the next shot, it's under her hair. They were dancing the whole time, so how could she or Derek have pulled her hair out of the chain?
Continuity mistake: In the scene where Aladdin is talking to Jasmine in front of the mirror the jewelled flower is in a vase with a real flower when the monkey under the table takes the real flower and the scene cuts back and shows the vase with both flowers. Seconds later the vase is completely empty.
Continuity mistake: The whites of Simba's eyes change frequently through the movie, from yellow to white. They're yellow up until the scene where Pumbaa, Timon, and Simba are stargazing; after that they change back and forth frequently. During the Mufasa-in-the-sky scene, when Simba asks, "How can I go back? I'm not who I used to be," they change from yellow to white and back within three frames.