Continuity mistake: In the "Be Our Guest" song a brown dish with a spoon in it approaches Belle, but in the very next shot the spoon is gone.
Continuity mistake: When Gaston tries to kiss Belle, his hands go from being on the plank of the door, to under it, to on it again.
Continuity mistake: In the scene where Maurice is sitting next to the fireplace, there is a picture with a silver frame on one of the walls. But after the Beast has burst into the room, there is a shot of the chair Maurice is in, and the picture is now in a gold frame.
Continuity mistake: After Phillipe's reins get caught in the branches, the loop of the reins becomes longer between shots.
Continuity mistake: When the Beast bursts into the West Wing after Belle refuses to go to dinner with him, he grabs the magic mirror, sees Belle, and puts it back down again. Then another petal falls from the rose, but notice that the petals on the table are in a different position than they were in the previous shot.
Continuity mistake: When Maurice comes to the fireplace the stairs are red, but when the Beast finds Maurice there and Maurice says, "I just needed a place to stay.", the stairs are now white.
Continuity mistake: Throughout the movie, the hour and minute hand that make Cogsworth's moustache keep changing sides, sometimes from one shot to the next, for example, when he makes Belle visit the castle.
Continuity mistake: When the Beast brings Belle into the library, there is a huge globe on the ground, but in the next shot, as Belle passes over it, the globe is much smaller and is now on the table.
Continuity mistake: In an overhead shot as the villagers enter the castle, there is a blond man in a brown coat carrying a torch. A second later, as the brawl begins, this man's torch has been replaced by an axe.
Continuity mistake: In the very short scene where the Beast throws Maurice into the machine and it carries him away, the front entrance of the castle is utterly different from normal. For instance, normally there are no stairs leading up to the castle, the statues on either sides of the doors are different, the walls next to the entrance are shaped differently, and so on.
Continuity mistake: In the scene where Lumiere and Cogsworth are persuading Belle not to go to the West Wing, the width of the red carpet on the stairs changes, it becomes much wider between shots.
Continuity mistake: When the Beast brings Belle into the library the books on the table change between shots.
Continuity mistake: When Belle returns the book to the librarian, he puts it on a shelf, and it is leaning against other books. A little later, it straightens itself without the man touching it.
Continuity mistake: When Cogsworth gives the tour to Belle, he is walking a very far distance from Belle. Yet in a closeup, he is walking much closer to Belle.
Continuity mistake: Just before Gaston proposes to Belle, the band members at his wedding change between shots.
Continuity mistake: Early in the film, we see the enchanted rose, and then the camera zooms away from the Beast's room and the castle. We see that there are several aspects of the castle that change during the Beast's fight with Gaston. For instance, in this shot we see that there is no window and the room opens directly to the balcony. This changes later. Second, the space along the roof is not as wide as it later is, and definitely not wide enough to have a fight. Third, we see strange statues of creatures that later appear in the fight- but no long row of these creatures such as appears later.
Continuity mistake: In the stained glass introduction, the rose in the beggar woman's hand keeps changing. Sometimes she is clutching it at the top, sometimes at the bottom, sometimes pinching it with her fingers.
Continuity mistake: When we first meet the three blonde triplets, the one in the green dress has the Ariel-like bangs, but in the beginning of the Gaston song she has swapped hairstyles with her sister in the orange dress. When Gaston starts singing about eating eggs they switch back, but during the last shot of the song they're both sporting the red sister's hair.
Continuity mistake: When Mrs. Potts is singing during the song "Be Our Guest", the spot doesn't actually appear on her until she notices it.
Continuity mistake: Between shots of Gaston throwing the bag of gold on the table and the man taking a coin out, the bag opens by itself.
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.