Continuity mistake: Towards the end when Glen cut his father's arm off, you see him lying there screaming and bleeding. The blood from his arm on the floor is making a puddle and then it cuts to Glen's face. When it shows Chucky's arm (or stump) again, there is no puddle, just blood following the crack in the floor tile.
Continuity mistake: When Joan walks in to see Tilly and Stan tied up on the bed, both Tilly's and Stan's feet are tied to the bedrail but are lying flat on the mattress. When Joan is set on fire, there is a shot where you can see Tilly's and Stan's feet again, only this time, they are elevated and resting on the bedrail they are tied to.