Continuity mistake: When the villagers are marching to the castle, in a wide shot Gaston holds the mirror with his left hand, but in the next shot as he yells "We will siege to the castle" it's in his right hand.
Continuity mistake: When Maurice is taking his invention to the fair, there is a covering over the machine with a brown patch on it. But in the shot where Maurice says "It's a shortcut, Phillipe", the patch is now white. Also, when Phillipe comes back to the house later, and Belle takes the machine off him, the patch has disappeared.
Continuity mistake: When Maurice lets Lumiere fall to the floor, the cracks Lumiere is over change between shots.
Continuity mistake: There are a row of nails in the bottom of the front of Belles wooden porch door which disappear later in the movie. (00:18:05 - 00:48:45)
Continuity mistake: When Chip rides Maurices woodcutter towards the cellar, between shots the barn door goes from open to closed. (01:11:55)
Continuity mistake: In the newer version on VHS by Disney, including the song 'Human Again', that added scene completely messes with the movie. During the scene the servants clean up the castle and make it pretty and happy. However, when it switches back to the scenes from the original movie, the outside of the castle is no longer clean until the end of the movie and the spell is broken.
Continuity mistake: When Lefou is jumping on peoples' heads singing "You can ask any Tom, Dick or Stanley" the position of the beer mugs on the table change between shots.
Continuity mistake: When the Beast is watching Belle from the balcony, the snow on the edge of the balcony changes between shots.
Continuity mistake: When Maurice is walking away from his house the tree next to the house is shaped slightly differently than the in the last shot of the house before that.
Continuity mistake: When Gaston flies into the muddy pond, Le Fou walks to the edge of the bank and right by the bank is a large bush of long green reeds. However when it cuts to a closeup of Le Fou saying "So, how'd it go?", the reeds have vanished. Reeds also apppear in the background, around the pond. (00:18:10)
Continuity mistake: When the trolley cart comes screeching through the lounge and knocks Cogsworth down, you see that Mrs. Potts, Chip and the milk and sugar pot are on the cart. Then when it cuts, and the trolley screeches to a halt beside Maurice, who's sitting down, the milk and the sugar pot have vanished from the trolley. In addition, after Maurice takes a sip out of Chip the teacup, in the following shot of the trolley, a spoon has appeared on it. (00:15:00)
Continuity mistake: The brightness of the yellow quivers of Gaston's arrows change during the final scenes. For instance, when he's outside and yells "But remember, the beast is mine!" they are quite dark yellow, but as he puts one in his quiver to shoot the beast, they are bright yellow.
Continuity mistake: When the Beast brings Belle into the library, the axis on the globe goes all the way through. A few seconds later, the globe is shown again, and now the axis only goes halfway up the globe.
Continuity mistake: When the Beast first shows Belle into her room, when he leaves you can see the doors have a curvy, spirally pattern which leads down the them. But when Belle is up in her room crying and Mrs. Potts comes to her door, Belle then approachs the door and we see the design on the door is now two large squares. However in the following shot of Mrs. Potts entering, saying "I thought you might like a spot of tea", the design has changed back to the curvy, spirally pattern. (00:24:45 - 00:30:15)
Continuity mistake: When Lumiere is being introduced to Belle and kissing her hand, the "hand" holding hers is lit and unlit between shots.
Continuity mistake: In the newer version of the film, there has been a new song called "Human Again" added, the wardrobe is about to dive into the fountain from a balcony. As she does, Mrs. Potts and Babette run away twice between shots. (01:01:25)
Audio problem: When the coathanger plays the violin during the title song, the sounds that are heard don't match him playing it.
Continuity mistake: When Belle and Beast raise their bowls, the oatmeal on the table has vanished.
Other mistake: After Lefou is stabbed in the butt by Cogsworth, there is no hole in his pants. This is impossible, since the scissors did pierce him.
Continuity mistake: During the brawl between the villagers and the objects, Lefou holds a torch in front of Lumiere. Wax drips down all over his face. In the next shot of Lumiere, the wax is gone.
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.