Continuity mistake: After Chip taps the spoon its position changes between shots.
Continuity mistake: When Cogsworth falls down the stairs while trying to stop Maurice from going into the room, a lot of his clockwork falls out and lands on the stairs. But in the next shot, it's all gone.
Continuity mistake: In the scene where the villagers try to imprison Maurice, there is a lot of snow on the stairhandle. When Belle comes out later crying "My father's not crazy", the snow is gone.
Continuity mistake: When Belle enters the West Wing, there are no candles next to the door. Later, Gaston enters with his bow, and now there are several candles next to the door.
Continuity mistake: During the fight scene at the end, knives are thrown at the villagers. Nobody is hit, but three knives get stuck in the left kitchen door. The villagers open both kitchen doors and, from the inside of the kitchen door, there are only two knives, each stuck in the right kitchen door.
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.
Continuity mistake: When the Beast is waiting for Belle to come to dinner, there is a fireplace with statues of lions on either sides and a pillow next to one of them. However, a few seconds later, the pillow is now in front of the statue.
Continuity mistake: In the scene where Maurice's Rube Goldberg-ish woodcutting invention works for the first time, we see the piece of wood fly over onto the stack. There is no window there or anything made of glass for that matter, yet in the next shot we hear glass breaking from the wood flying over there.
Continuity mistake: At the end of the Provincial Life song, Gaston is singing from among the crowd and he doesn't have his gun. He climbs up the side of the building without his gun, but when he pops out of the window onto the roof he has his gun. When he pops in front of Belle on the street, the gun is gone again. (00:07:05)
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.
Continuity mistake: In the opening song sequence, there are three blonde girls singing about Gaston next to a water pump. But in a front shot of Gaston walking through the city as they sing, it is a barrel, not a pump, that they are gathered around.
Continuity mistake: When Maurice first enters the castle you can see that the carpet leading to the staircase is very long. When Belle enters the carpet is shorter.
Continuity mistake: After Lefou is soaked he disappears in the very wide angle of Gaston walking behind Belle. (00:07:33)
Continuity mistake: When Gaston says he'll make Belle his wife a woman with a grey colored hair suddenly appears out of nowhere in the close-up. (00:07:58)
Continuity mistake: When the three girls first see Gaston, the fountain is pouring loads of water into the bucket. A shot later the water has suddenly stopped and the girl in red has the bucket raised up to her waist.
Continuity mistake: When Gaston proposes to Belle he kicks off his boots, which disappear in all further shots.
Deliberate mistake: During Be my guest song the menu suddenly disappears from Belle's hands between shots. (00:39:39)
Continuity mistake: When Mrs. Potts puts Chip into the cupboard, the handles change style and colour: from gold to black. Also, the carvings on the wood become blue painted for a brief shot.
Continuity mistake: Beast bursts into the West Wing, uses the magic mirror and puts it on the table. A shot later it has vanished. Note the shape of the rose between both shots and you'll notice that it's not an opposite angle. The mirror is definitely gone.
Continuity mistake: When the Quiet village song ends, the sign on the last house on the right swaps from green to brown coloured between shots.
Answer: The Rose started wilting at The Beast's 21st birthday and could have presumably started wilting years before the first time we saw a petal fall off. Given the fact that Lumiere stated that they were living with the curse for 10 years, prince Adam could be 23-24 years old at the time of the original movie,13-14 at the time of the curse, and the Rose could have been wilting for two to three years. This is my best guess given the approximate age of Prince Adam in the ripped up portrait before he was the Beast.