Easter egg: If you have the regular Child's Play DVD (the one with Chucky looking at you with a scrunched, evil face while holding a knife), go on the bonus features, go to the second page with the behind the scenes features, and press "right." Chucky's eyes should turn red, so press enter, and you'll get a very brief, animated version of Chucky saying "Hi, evil comes in little packages, like me."
Easter egg: If you have the Child's Play DVD with Chucky slightly turned and with a scrunched, evil expression, and while holding a knife, go to the bonus features and on the first "page" (Chucky looking down at Andy), press "right" on your remote. Chucky's eyes should turn red, and if you press "enter", you'll get a very brief, animated version of Chucky saying "I'm the original designer toy."
Chosen answer: This isn't a mistake. John made the voodoo doll himself. When Chucky said he was "prepared" for it, he meant that he was prepared to do whatever it takes to get information from John about his being wounded. Even killing him as we see.