I do know that one in bonewerkz with the drills and the shrykalls. And also the laughing gas one (though i did have to do it twice).
I'm not sure what you mean about the mine cart, and i've found the three before the brewery entrance (behind a barrel in feeco depot).
But it doesn't really matter now cause my new computer is to bloomin stupid to work the game.
I HATE COMPUTERS, ESPECIALLY STUPID NEW ONES THAT CAN'T RUN OLD PROGRAMS!