Revealing mistake: When Grace falls to the floor, copies of her face keep pouring on her. Two are shown up close pouring out, and they are different from each other. One has a big hole of cracked glass covering her right eye and the other one shows her right eye without the hole at all. One copy was taken before she fell so two different looks over her eye is not possible.
Continuity mistake: Early in the film when the Chucky doll is being rebuilt, he is put together limb by limb and has a hard plastic body. When the doll is complete and seen in later scenes throughout the movie he has floppy arms and legs which would indicate a stuffed soft body doll. The good guy doll was shown as a soft body doll several times in the first film, like when Maggie picks him up from from in front of the TV by his arm. (00:03:10 - 00:15:30)