The pants are almost the same color as the skin, and you'll need some differentiation for that. Nevermind (hopefully) if you wanted to keep the limits the same. All I'm asking is to see more shades. Right now you have me thinking I'm partially color-blind.
As well, the zombie's feet never seem to get off of the ground (the closest to that they seem to have gotten is when the nearest foot lifts half-way) yet seem to lack much friction, like the zombie's walking on ice. The only way this could be fixed is slowing this down, I suppose.
Another problem I have is that the the hand of the outstretched arm is tilted the wrong way. Either that or it's a crab's claw. Try tilting your hand that way and you'll find it's rather uncomfortable. Not impossible, just uncomfortable. Besides, since hands aren't positioned like that naturally, try tilting them the other way, at least so the fingers are visible.
Also, perhaps more left/right movement should finish the arm off, less of a feeling of rigidity, and more a feeling of elasticity--after all, it is a zombie, and its arm might as well be falling off. (And maybe more bouncing on the speech bubble while you're at it. And tone down the anti-aliasing if you like.)
Here be edit:
Palette suggestions:
Less saturation. This is a zombie. It's dead, even if it isn't. Try to suggest that with more "dead" (desaturated) colors. Even if it is stylized. Right now, most of your palette's at full saturation.
Exposed flesh tones should have more reds in them. Purple is pretty much the opposite of green. This is further accentuated by the drastic change in value (flesh is dark compared to the light skin, even surrounded by anti-aliasing). After changing it to red, I wondered what it might look like serving as a color for the pants. IMO, it worked out pretty well, but might need to be brighter still.
Made more use of highlights. It may have destroyed the "cel-shaded" look, however, but it does reinforce the presence of an exact lightsource.
