my arms and Kenny's face don't seem to go together...
they need to be done separately - ergo the usefulness of mattes.
on some shots I've had as many as two dozen mattes. (maybe more. my memory on this is fuzzy).
anyway, as I think about this, the "trick" is to see this scene as 3 dimensional. you have to imagine not only what you see but what is behind and around the scene. like where is this light that "seems" to be on "Kenny"? what kind of light? where is it pointed? what color is it? and so on. i know there isn't a REAL light. but to make a composite work, you have to imagine these sorts of things. that affects how you have to alter things to fit inside this imagined place.
If I had to do this for a real job - and not a comedy moment - i would have fixed Kenny's face first thing. as it is now, all the information has been removed from it. whenever you lighten or overlighten an image you remove information.
a real job would hopefully have better source pic. altho, now always :-)