Well it's impossible to get an achievement that doesn't exist. If you are trying to get "Monster Lover" achievement then you can't hurt any kind of monster, on any level for the 2000 km
Here's a hint on the drinking zombies achievement, if you still haven't figured it out: you have to kill a specific number of monsters in one run.
Fantastic game! 3rd game I've ever bought since my venture into iPhone (Jan2010), and am not regretting it. Provides loads of entertainment. Don't know if this have been mentioned but was wondering if the pause button could be larger? It's difficult for me to pause the game sometimes due to it being too close to the top left corner. Other than that, this game is almost perfect ~