Judging from your picture, I have pulled a similar looking casting of Dragonskin out of a Rebound 40 brush mold.
My guess is you did this: you have a sculpt, you brushed on a silicone, and then cast silicone in silicone-- but your end product has holes on it.
This could be a result of your mold-- what happened to me is I used too stiff of a brush, and in trying to push Rebound 40 into the crevices of my sculpt, I poked little holes in my clay sculpt. So my mold ended up with whispy hairs on it that gave me some mangy looking castings.
It also resembles a silicone casting I took out of a rough quick plaster lifecast I took of my face-- the air bubbles and rough nature of plaster gave me a pitted resin casting and bumpy silicone copy, too.
I think your problem is with your mold. Look at the inside surface and see what it looks like; if it's rough, then your casting is going to be rough. You might need to make a new mold.
If the above is not your situation at all, then try this:
Thin your casting silicone with silicone thinner. For some reason your casting rubber might not be reaching all the small places in your mold and so you're missing some detail, or it's forming bubbles for some reason. Also try using a soft brush to brush on a first thin layer of silicone in your mold to capture surface detail, let it cure to "tacky," then pouring the rest of your casting.