Continuity mistake: The settings and conditions of the West Wing change drastically. For instance, in the beginning, the painting is very close to the rose and there's also a red carpet underneath it, but later the painting is further from the rose and the red carpet disappears. When Belle leaves the room after the Beast releases her, there are red decorations on the floor in front of the door which were not there earlier when the Beast burst in after Belle refused to go to dinner with him. There is usually a lot of junk cluttered in the West Wing, but when the Beast takes a bath it looks much cleaner. It's an almost endless list.
Continuity mistake: When Belle sees Maurice's machine for the first time, the axe on the machine changes between shots.
Continuity mistake: When Gaston spits out the bit of belt during the 'Gaston' song, there is a frog decoration visible. It wasn't there in the opening shot of the tavern though. (00:25:10 - 00:27:20)
Continuity mistake: When Maurice enters the castle doors for the first time, he walks forward, calling "Hello ... Hello?", and there are clearly TWO pillars at the side of the door. Then, in the overhead shot, when he calls "I don't mean to intrude...", there is only ONE pillar!! (00:13:15)
Continuity mistake: When Gaston and Le Fou talk to the Asylum Keeper, in a wideshot Gaston finishes his beer and puts the beermug down. Then in the shot when Gaston says "I've got my heart set on marrying Belle", the mug has vanished. It then returns in the following shot. (00:48:00)
Continuity mistake: When Maurice enters the castle for the first time, there are windows on either side of the front doors. These were not there when Maurice had looked up at the castle after arriving.
Continuity mistake: The length of the chip on the axe in Maurice's invention changes in the scene where he is building it, and also later when Chip is trying to get it to work.
Continuity mistake: During "Gaston", Gaston shoots his blunderbuss three times. However, four holes appear in the ale barrel.
Continuity mistake: After the brawl between the villagers and the objects, a lot of mess is on the floor. Then when the objects jump for joy, the mess is gone.
Continuity mistake: When Maurice gets his woodcutter working in the cellar, the axe starts cutting a log which is in a wooden bench, which sits in front of the woodcutter. However when Belle entered the cellar earlier, through the clouds of dust, the area in front of the woodcutter was empty. (00:08:45 - 00:10:05)
Continuity mistake: In the shot of Belle reading her book in her house, the spout of the black kettle on one of the shelves is not visible. In the following scene, when Gaston is talking to Belle with his feet on the table, the spout is visible.
Continuity mistake: When Gaston is cleaning his teeth in front of the mirror, the decorations on the mirror's frame change between shots.
Continuity mistake: When Maurices invention explodes, Belle runs to the house and into the cellar. As she enters, you can see the area in front and around the stove/fireplace is empty. However after talking for a while, Belle says "...oh Papa, he's not for me" and sits down on a wooden stool which has suddenly appeared in front of the stove/fireplace. (00:08:45 - 00:09:45)
Continuity mistake: When Gaston falls out of Belle's house when she opens the door suddenly, Gaston lands in the pig pen. He gets up, grabs his friend, throws him in the mud, then walks away. In the background you see Belle's house. How could he fall down the stairs and what looks like over 20 feet away into the pig pen? (00:18:00)
Continuity mistake: In the dance scene, Chip is sent off to bed but comes back to watch. You can clearly see Chip's reflection in the floor, but he has no mouth. (01:02:25)
Continuity mistake: When Maurice looks into the castle after arriving, there are no yellow edges around the red carpet. Yet moments later, they appear.
Continuity mistake: When the Beast claws the painting of himself in human form, he tears his right eye. When Belle comes into the West Wing later, neither of his eyes are torn.
Continuity mistake: Just before the new "Human Again" song, Cogsworth is telling the other servants what to do. He is standing on the dog/footstool and tells everyone to clean up the castle. All the servants run off including the dog/footstool and Cogsworth falls down the stairs. A load of cogs fall out of him and Lumiere picks one up. It is quite small but as he dusts it off it grows and when he hands it to Cogsworth and it has grown in size again to over double the size it was when it first fell out of him.
Continuity mistake: When Gaston jumps from the rooftop in front of Belle and says "Hello Belle", he has four arrows in his quiver. However in all the previous and following shots, he only ever has three. (00:07:35)
Continuity mistake: In the Gaston song sequence, the villagers pick up the chair Gaston is in, and carry it in front of the bear rug. Then suddenly, Lefou is standing on the bear rug, and the chair crashes down on him.
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.