When I cut my soap into bars I noticed tiny holes. No discoloration. I tapped mold down after pouring. Did I perhaps not pour soon enough and batter was too thick to properly tap all of the air pockets out?
If they are tiny, pinpoint bubbles, they are probably caused by your stick blender. It happens when air is trapped under the bell of the SB, and when you submerge it into the soap batter, that air gets mixed in when you turn the blender on. You can try "burping" the blender, by bouncing it on the bottom of the pot, forcing the air out, or inserting the SB at an angle, so the air can escape. This may work, maybe not. Some people say that certain SBs suck air down the shaft into the batter. I tried all the tricks, without success. But when I bought a back up SB at the discount store, and tried it out, I discovered that the cheapie SB did not cause bubbles, so it became my primary SB. It is just cosmetic, and the tiny bubble don't bother a lot of people, but some of us like to see smooth soap, so it may be worth trying some of the tricks, or maybe a cheapie (like $10) replacement. HTH
P.S. I meant to add that this type of bubbles can't be removed by smacking the mold on the counter. :-(