Hello!
It seems there is a bug with Machinarium with Mountain Lion. In prison (screenshot at this address :
https://dl.dropbox.com/u/15426385/Bug_Machinarium_MountainLion.png), once you were afraid to prisoners of the neighboring cell with the arms of our cellmate, the robot remains stationary while everything else continues to animate, and it is no longer possible to play.
Luckily, the menu is still usable, but not progression.
Sincerely, Marc ou Net.