When you define the mask type on several layers it's like if you "reset" the mask. AS takes the layer order as reference to mask. So "head" is only masking "head shadow". Then "static mouth" is masking only "mouth shadow" and "eyes". Then "hair" is masking only "hair shadow". "Left ear" is a mask, but actually it's not masking any layer, because there are no one layer over it on layer order.
On your original file, you have defined the mask type (+clear the mask, then add this layer to it) on every layer you want to be a mask. That's the problem with the eyes, they are being masked by "static mouth" layer, but not by head layer. Try translating the eyes bone layer down over the mouth and render. You'll see what I'm talking about.
There are two solutions I see:
The easy one with this file is take the eyes bone layer and put it between "static mouth" and "head shadow" on layer order. If you render now the eyes will be masked by "head" layer and not by "static mouth" layer.
Now, the other solution is to re-think the way you are masking (I recommend this one for your future files). I have a example file for that you can download
here. I put all shadows on a single layer, then put this layer over all the others on layer order.
To keep things simple, when you are masking, you define the type of mask on only one layer ("head" in this case), then on the others you don't re define the mask type, you just select "add to mask". This way you create a single mask made by all your masks layers together. So in this case "head", "static mouth", "hair" and "left ear" are being the single mask for "eyes" and "all shadows" (I prefered to let "eyes" bone layer masked too because if you want to do a little head turn it will be easier if the eyes don't go out beyond the head limits).
So, as resume, a mask layer only masks the layers which are over her on layer order. If you define a new mask type (or re-define the same) on a layer which is in any place over the previous mask, the first mask will lose his powers for the layers which are over that new mask. To avoid this, instead of define a new mask, you must select "add to mask".
I hope to be clear. At first masking is a tricky technique, but once you understand how it works it's pretty easy to create complex maskings.
