Revealing mistake: When Nica crawls to the elevator to escape Chucky, she bends her legs in order to shut the elevator door. She is meant to be a paraplegic and have no feeling in her legs.
Revealing mistake: When Nica goes to investigate the screams in the first part of the movie, as she opens and closes the door she appears to be moving in a way that implies she is standing and not sitting in her wheelchair, this completely contradicts her being a paraplegic.
Revealing mistake: When the pastor is beheaded you can see a clear tube inside his neck that is squirting blood.
Revealing mistake: When we see Jill's webcam image on the remote laptop during the electrocution scene it is from Chucky's point of view, and not her laptop's webcam.
Revealing mistake: When Chucky is trying to kill Nica with the fumes of the car, you can hear him hit the gas and the engine revs, but the smoke from the silencer has a constant flow.
Answer: It is revealed when Ian checks the webcam that Chucky hid Alice in the closet. She was most likely there the whole third act.