Audio problem: When Mrs. Potts is talking to Belle for the first time, in her bedroom, Mrs. Potts says "It'll turn out alright in the end. You'll see." However, when she says "...you'll see" her mouth remains closed. (00:30:50)
Audio problem: During the fight scene at the end, Gaston says, "It's over, Beast. Belle is mine." But, originally, Gaston said "time to die" instead of "Belle is mine." (They wanted to involve Belle more in this scene, and decided to simply overdub the line). Unfortunately, you can tell what's been done, for Gaston's lips still say "time to die."
Audio problem: In the first shot of Gaston losing his balance, he cries "Woah, ah" or something, but his lips don't move.
Audio problem: Gaston throws his metal beer mug into the fire, and we hear the smash of glass.
Audio problem: When the coathanger plays the violin during the title song, the sounds that are heard don't match him playing it.
Audio problem: At the beginning, when the explosion occurs in Belle's house and Belle goes into the cellar to investigate, she says "Papa?" but her lips don't move at all.
Audio problem: When the horse comes galloping into the meadow, Belle cries "Phillipe" but her lips don't match what she's saying.
Audio problem: Maurice's machine starts working and one of the logs hits him with a 'thunk', yet the sound of the log hitting the ground is never heard.
Audio problem: During the scene near the end when the enchanted objects are fighting Gaston's gang, there is a close-up of a pot landing on a guy's head and then starts banging on it. The clanging sounds we hear do not match with what we see.
Answer: In the prologue, it states that the Beast must find true love by his 21st birthday, and that he had been cursed for ten years, so since his relationship with Belle takes place as the deadline approaches, he must have been 10 when he was cursed.