Plot hole: Not far into the movie, Starla decides to check out the basement to see what Grant's been up to. As soon as the door is opened she reels from the stench and we discover that it's full of rotting meat and dead animals. In reality, the whole house would have smelt like an abattoir for days before hand and the stench would have permeated out into the neighbourhood. A non-airtight wooden door would not have kept that kind of smell located to the basement only.
Plot hole: When John is painting the doll's face he looks down at a photo printout of Amanda, you will notice the bruising/scratches on the side of her face in the picture. Please take note of her hair, shirt and overall demeanor. Now think back to the first Saw when Danny Glover had Amanda in the interview room. The picture that John Kramer is looking at is a picture taken of her in "that exact" interview, this is strange however considering that the interview took place after she escaped the jaw splinter, so how does John have a picture of her from the future? (00:51:40)