Naw the handcuff just does extra dialogue. I've been looking into why the zombie disappears. (She's not supposed to do that until after you get the CJ) but I've been swamped with work related business lately so I've had trouble pinning it down.
Rex scared the zombie off! That must be it! I think, outside of "figuring out what the heck the 3 digit code is for the toy box thing" I've seen pretty much everything I can. There's a few things that you are teasing (if I can get the "cartoon crush" I'm not aware of how, and if the knife and the duct tape have a use yet, I'm not sure what) and I noticed a Red Green show reference (possibly unintentional)
My only real complaint is there's some things that don't make sense. The MC talks about not visiting the sucurity place unless the others are trapped in the freezer... before even knowing that they can be so. Also there was a task about getting Rex some help from a wolf attack before it even happens. It doesn't take away from how fun the game is(and it is really fun), just...weird word choice sometimes.