Continuity mistake: There is a scene with Belle and Beast dining. Beast wolfs down his meal out of the dish and his face is covered with food. Belle looks shocked, so Beast then tries to use a spoon and he is completely clean. Belle smiles sympathetically and Beast is covered with food in the next shot. When they are both eating directly from the bowl, Beast is clean again. It is the same meal. The food is missing from his face, although not an uncommon thing for animators (especially of kids films) to do on purpose, Disney probably wouldn't consider it a mistake, but rather, a convention, to make the characters always look their best. (00:51:30)
Continuity mistake: At the end of the 'Something There' song, Belle is sitting at the fireplace and Beast hangs her coat up on a stand. Next to the coatstand you can see a bookcase with a statue on top of it. However when it suddenly cuts to Cogworth and Mrs. Potts, who are watching them from the doorway, still singing, the coatstand, bookcase and statue have all vanished. (00:53:25)
Continuity mistake: In the slightly changed version with the song 'Human Again' added, when Cogworth, Mrs. Potts, Chip etc. are talking about there being "Something there that wasn't there before...", just after the "Something There" song, In this scene Chip's chip is in the left side of his cup. It is meant to be in the right. (00:53:35)
Continuity mistake: In the newer version of the film, there has been a new song called "Human Again" added. When standing at the foot of the stairs, Cogsworth replaces a cog in himself, opening his door, with the hinges on his right. All the other times he opens it though, the hinges are on the left. (00:54:35)
Continuity mistake: In the newer version of the film, there has been a new song called "Human Again" added. When the little dog-like footrest runs across the hallway, chasing the cat-like cushion, he leaves black footprints all over the floor, and then he skids to a halt, leaving circular swerve marks over part of the floor. However when it cuts to an overhead shot, the line of footprints along the floor runs much shorter and there are now more sets of swerve marks. (00:57:25)
Continuity mistake: In the 'Human Again' song, near the end of the song Cogsworth and Lumiere turn on the fountain and the large middle statue sprays out water, but the two statues either side of the middle one are turned off. Then the wardrobe jumps out onto the balcony singing and then it cuts to an ariel shot, and now the two side statues are suddenly spraying water too. (00:58:45)
Continuity mistake: When the Beast is getting ready, just before the ballroom scene, the coat stand is cutting the Beast's hair with a pair of scissors that has red handles. Then, in the final shot, the whole pair of scissors is silver. (00:59:40)
Continuity mistake: In the newer version of the film, there has been a new song called "Human Again" added, the wardrobe is about to dive into the fountain from a balcony. As she does, Mrs. Potts and Babette run away twice between shots. (01:01:25)
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 Belle and the Beast go and sit outside after the ballroom scene, when the Beast asks Belle "Are you happy here with me," between shots Belle's hair goes from being normally hanging down by her back, to resting over her right shoulder. (01:02:45)
Continuity mistake: At the end of the movie, Belle shows the Mirror to Gaston and the other people in the village. She's wearing a white apron over her blue dress. When Gaston takes the mirror from her, the apron is gone. A few seconds later, it's back. (01:06:35 - 01:07:20)
Continuity mistake: When Gaston is telling Belle all she has to do is marry him, and her father will be let go from the asylum, his hands are bare. Then when Belle gets the magic mirror and cries "Show me the Beast!", Gaston has yellow gloves on. Then in the next shot they're gone again. (01:07:25)
Continuity mistake: When Gastons mob throw Belle and Maurice into the cellar, Belle then tries to wedge open the window with a long wooden pole. She fails, then turns to Maurice, leaving the pole sticking out and laying on the windowsill. Then when the shot changes and the camera pans to Chip looking through the window, the wooden pole has gone. (01:09:40)
Continuity mistake: When Gastons mob start to bang the front doors with the tree trunk, in one shot of them banging, the door handles are gone. Then two shots later they've returned. (01:10:55)
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: When the household items fight the mob, six beermugs fling tomatoes at a man. It cuts and there are suddenly just five beermugs. (01:12:15)
Continuity mistake: When Gaston's mob comes and the dresser jumps on someone, she starts to jump down stomach first, but the next shot of her, she's feet first. (01:12:25)
Continuity mistake: When Le Fou and two other men chase the dog-like footrest, Le Fou has a pitchfork and the men have an axe and a sword. However when they bust through the kitchen doors, the sword has turned to a club. (01:13:10)
Continuity mistake: When Le Fou is chasing the dog-like footrest he is missing one shoe, which the dog has, but when Le Fou and the gang burst through the kitchen door, he has the shoe back. Then when the knives scare them away, it's missing again. (01:13:10)
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.