Continuity mistake: When Alvin is making the big SOS sign, one shot shows the whole beach and Simon and Theodore are in the middle of the big letter O. In the next shot, they are at the O's edge.
Continuity mistake: At the end of the first film Mumble has lost most of his down, because his bow tie has yellow markings, however in the second movie he has somehow grown his down back.
Continuity mistake: When Ren is dancing at the drive in, he starts dancing with a girl then stops to watch her. When he starts dancing again he moves slightly in front of her in the shot. Then in the next shot they are side by side.
Factual error: The term mayor of Paris was abolished from 1871 till 1977. But we see Victor Maynott wants to join the mayor campaign in 1910.
Audio problem: In Notes II, Madame Giry voice is out of sync as she says,"Fear his fury.".
Continuity mistake: When Gail introduces Guy to Bev, Guy's hand is under his chin in the foreground when Luke eyerolls at the whole ordeal, but his arms are all down in any other shot. (00:07:00)