Not exactly a bug, but a feat that has always intrigued me:
It doesn't help a player in any way, but it is a confirmation that mining locations are preset. I discovered it 1 time I played in Pie back on WON. If you know more or less the exact location of your backdoor rare bar, you can send your Robo Surveyor to that exact square, and it will perform the usual testing with its nose, then turn around and drive upwards so it stands right above the non visible future rare bar. Just as it will do when it fnormally surveyes a ore bar.
NOTE:
1) This will only work if you have not already researched Rare Ore.
2) This operation will not reveal whether you get a 1,2 or 3 bar rare, neither will the ore bar show up as previously surveyed mining location once you finally reasearch Rare Ore.
ps Lev, the wall thing your talking about is more precisely reffered to as "killing a square". After you do this nothing can be done with this particulare square. No building, razing, driving over etc. (Note, Lava will eventually overrun it though)
Antoher feat is that you cannot build a wall of these, you can only kill each second square: (X is dead square, Y is a normal one) XYXYXY
So you can not completely seal yourself or your opponent in...