There is a golden pickle hidden in stage 8. It is under where it says "like a trampoline"
You also get an acheivement for finishing the first nine levels.
A golden ice crem cone is hiddden in stage 19 on top, before the second wall.
After you finish stage 19 you get another acheivement.
After finishing stage 28 you get another acheivement.
There's a golden juice box in stage 29. On top of the box that says "applegates", before finishing , fall down to the left.
If you finish with less then 10 deaths you get an acheivement.
Also if you finish with no deaths you get a better acheivement