Continuity mistake: In the 'Gaston' song sequence, near the end, Gaston is sitting in his huge antler chair with Lefou. In the wide shot, there is a bear rug behind the chair. The camera does a close up of Gaston, then in the next wide shot, the chair is on top of the bear rug. Also, after this, Gaston gets up off of the chair and in the next shot, both the chair and the rug disappear completely. (00:29:20)
Revealing mistake: When Akane is sneaking out to the kitchen in order to cook something she briefly has a see-through hand, the animators haven't added any pigment and you can see the background cell perfectly.