Deliberate mistake: When Barb is in the attic, she finds two pictures of sunflowers in front of her. It then cuts to the "opposite" angle of Barb, and those exact same two pictures are suddenly behind her. In fact, everything behind her is the same. It appears to be two slightly different shots from the exact same angle that they tried to "cheat" as being two different angles. (They almost get away with it because the second shot is wider, but once you notice the pictures, it's far too obvious.)
Deliberate mistake: The video feed from Jill's laptop doesn't match the angle we see her laptop in. The image should be a weird, low-angle shot with lots of space above her head given her laptop is down on her lap, but the image we see is a pristine parallel shot. Additionally, the video footage is way too high quality for a 2013 laptop webcam. (Heck, it's too high quality for a 2024 laptop webcam.)
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.