Continuity mistake: Early in the film, Gaston throws Belle's book into the mud and she wipes it off with her white dress. However, no mud appears on her dress after she does this.
Continuity mistake: The amount of eggs which land on the floor / on LeFou's face is much lower than the the number which he threw up into the air. (00:28:40)
Continuity mistake: At the very end, when all the objects change back into humans, the position of the roses on the walls in the background changes between shots. (01:23:25)
Continuity mistake: In the scene where the villagers try to take away Maurice, the position of the vines over the cellar doors changes between shots.
Continuity mistake: When the Beast and Belle are in front of the fireplace reading the book, a pot magically appears next to the coat hanger.
Continuity mistake: When Maurice first comes to the castle, there is no smoke from any of the chimneys, even though we later see that there is a fire inside.
Continuity mistake: Outside Belle's house there is a wishing well situated on the grass directly in front of the window and cellar doors, plainly seen in the initial shot of Belle leaving her home to go to town. However in the scene where Chip gets Maurices woodcutter going, as it hurtles towards the cellar doors in a wideshot, the wishing well has vanished!! (00:02:45 - 01:11:55)
Continuity mistake: When Maurice is thrown out of the tavern, he falls into a thick pile of snow, near the fountain. However when he cries out "Will no-one help me?", the stone ground outside the tavern is suddenly all snow-free. (00:28:45 - 00:30:00)
Continuity mistake: In the opening shot of Belle's house, the gates are in the shape of Z's. Later, as she comes out of her house after Gaston has proposed saying "Me, the wife of that boorish, brainless." the gates are in the shape of X's.
Continuity mistake: When Belle approaches the door to let in Gaston, there is a plate near the door that is significantly circular. When Gaston comes in a few seconds later, the plate is more oval-shaped.
Continuity mistake: Right at the beginning of the 'Gaston' song, LeFou sings "no-one slick as Gaston", and we see a man chatting to a lady by the bar, with a barstool right behind him. Then LeFou runs to him and whips off the mans belt, and now the barstool isn't there. (00:26:00)
Continuity mistake: In the song "Provincial Life" Belle is sitting on the edge of the fountain reading her book. Between shots she moves further away from the fountain.
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: When the Beast discovers Belle in the West Wing, he starts yelling at her, and she backs into an old, rotting cupboard that sports many patterns and designs on it. Then when the shot changes the cupboard is suddenly new-looking and in good shape and has no patterns on it at all. (00:44:10)
Continuity mistake: When the Beast takes Belle to the library, he opens the doors outwards. Then in the following overhead shot, you can see the doorway clearly, however the doors have vanished. (00:50:20)
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.
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.