Here is the full list of all 12 Doc Clock: The Toasted Sandwich of Time achievements.
Destroy a robot using a robot head.
Propel your vehicle 150 meters into the air, using any means possible.
Destroy five robots in two seconds.
The gnome must be cast back into the fiery chasm from whence it came.
Collect 20 robot heads.
Pick up twelve toasted sandwiches.
Fall into a pit of lava 3 times
Perform a 540 degree flip in a vehicle.
Sound the bell ten times within ten seconds.
Sit in front of a TV for five minutes.
Collect 75 robot heads.
Complete every level without using the time slider.