blasterman is exactly rigt..lol..thats definitly the flywheel side and that hole is bigger than normal, and its from using something other than a flywheel puller to try and pull off the flywheel... screwdriver,prybar..etc..
I did that myself on another bike i use to own and fixed it with jb weld..and used a dremmel after to smooth it out ,so it was almost un noticable. other then water getting in your flywheel it isnt gonna hurt you much unless it cracked it strait through the whole case.
since then ive learned to always use the right flywheel puller !