Continuity mistake: When the villagers burst into the castle using the tree trunk, they put it down in front of the door, but later it's gone.
Continuity mistake: When Maurice is gathering his belongings and says, "Somehow I'll get her out of there.", to the side of the door there is an umbrella and a coat hanging slightly to the right of it. However, when Gaston bursts in, shouting, "Belle? Maurice?" the coat is now hanging directly over the umbrella.
Continuity mistake: When the Beast shows Belle her room, she walks in, and in the wideshot when the Beast says "Now if you need anything...", you can see the whole tiled floor around and under the bed is bare. Then seconds later when Belle runs to her bed crying, and the camera pans out the window, there is a large rug on the previously bare floor. (00:24:40)
Continuity mistake: In the kitchen, the stove says "I work and I slave all day long, and for what?" and the stone wall behind him is bare. Then when it cuts to a close-up of him saying "A culinary masterpiece gone to waste," two shelves have suddenly appeared on the wall behind him, with pots, pans and utensils on them! (00:35:30)
Continuity mistake: When Maurice is getting ready to go back to find Belle, and is pocketing compasses and rolls of paper, he takes a scarf from a drawer, leaving the drawer pulled open, with a red scarf hanging out of it. Then when Gaston and Le Fou enter the house, the drawer is pushed shut with no red scarf hanging out. (00:48:45)
Continuity mistake: When Belle and the Beast eat breakfast, in the scene where the Beast gets covered in porridge, in front of Belle is a decorated glass and a basket of rolls with a napkin over the top. In front of the Beast is just a decorated glass. During shots we see neither one, nor anyone else touch these items. However in the final shot of the whole table, in which Belle and the Beast raise up their bowls, the basket of rolls and the Beasts glass have both disappeared. (00:51:15)
Continuity mistake: When Gaston climbs out of the muddy puddle, he storms off, and it shows Belle's house in a wideshot, with the stone walls surrounding the porch with nothing on them. Then it cuts to a closeup of Belle emerging from the door, but now there's a bucket of seed, and some chickens on the walls. (00:18:30)
Continuity mistake: When Belle's father is in the woods being attacked by bats, when he runs toward screen the bats suddenly disappear. (00:11:40)
Continuity mistake: Adding to the mistake about the bear rug moving around, it also changes physical form. Sometimes it is a light brown, fat and un-realistic looking. Other times it can be seen as a dark brown/black flat bear which looks very real. This change occurs many times during the scene.
Continuity mistake: Whilst Maurice sits in the Masters chair, Cogsworth is knocked down by the trolley with Mrs. Potts on it, and he falls down on the large red part of the carpet. It then cuts to Mrs. Potts, then back to Cogsworth who is still lying down, however now he's suddenly lying on the white part of the rug. (00:15:00)
Continuity mistake: When Belle uses Maurice's invention to look outside the door, there is a wooden bolt on the wall. The length of this bolt changes between shots.
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.
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.