I recently had a buffer get stuck under the inside of the rear jack point of my clk320.

I noticed 3 tubes under the vehicle and one of the tube was pushed upward towards the floor pannel. I also noticed a small crack on the underbody.

I am worried that this might cause a problem in the long run due to more cracking and leaking of the tube.

I thought about just using a plier to unbend the tube back to it's original shape, but I decided not to.

Do I need to replace the tube or can I just ignore the problem.

The car drives fine, but I'm worried about the future.

Sounds like the fuel & vapor lines by your description. Have the car inspected ASAP by a good tech. Get the car on a lift & take a good look.