The black circle things from the bottom of my macbook pro came off...

I think you mean the small "feet" on the bottom. If you take it to your local Apple retailer they should be able to replace them or provide you with replacements you can affix yourself. Or you can visit ifixit.com to see where you can buy replacements.

The only damage that could be caused is scraping the bottom cover of the computer should you drag across a rough surface.

Katte & Kappy:

I know it sounds highly unlikely, but actually — yes, they can fall into the computer. My testament:

First, take a look at the photo in this thread I posted a few months ago, which shows an unidentified object that I found in my MBP: https://discussions.apple.com/thread/3891749. Since I assumed it had broken off from something inside the machine, I looked around online for schematics, parts diagrams, etc. to try and figure out if it was something "mission critical." Since I didn't find anything and I never got a response to my post, I eventually gave up and wrote it off as an unsolved mystery.

Fast forward to last night... After finding a rubber "foot" on my desk, I turned the MBP over to see which corner it came off of — and I immediately recognized the black plastic fragments that were sliding around in a circle of gooey sludge (glue/adhesive) where the foot used to be. Here's a shot of it (that's the underside of the foot sitting next to it):

I'm no expert, but considering: A) the physical & visual evidence; B) the fact that the faulty foot happens to be in that particular corner; and C) numerous reports from MBP owners who lost the same foot .... I think it's fair to assume this foot malfunction is heat-related. I read in another thread that Apple knows about it and will replace the entire bottom panel for free, but apparently the program is only for MacBooks. (No love for Pro owners?)

As for how one of the fragments got inside the machine, I'm guessing it slipped out from under the foot and got sucked into the fan vents. While I'm glad to have finally identified the mystery object, I'm a little disappointed that Apple won't fix something that is clearly a design flaw.

@Katte: It might not be a bad idea to just unscrew the bottom panel to investigate that loose object. If it is part of the plastic footing, I imagine it could melt if it ends up resting on or near something hot.

Just as an FYI, here's that MacBook replacement program I mentioned: http://www.apple.com/support/macbook-bottomcase/

The replacement program you cite is for a "monobody" shaped MacBook, but with a plastic (not metal) bottom. The bottom is completely coated with a rubbery material.

They have decided to replace certain bottoms if they de-laminate. This has nothing to do with metal bottoms with rubber feet as in your MacBook Pro.

Check out this support article:

http://support.apple.com/kb/HT5236

Ciao.

Lots of information and options here:

http://www.google.com/search?q=macbook+pro+feet+replacement&ie=UTF-8&oe=UTF-8&hl =en&client=safari

No, they cannot fall into the computer.

Some Hard drives, even when off, make a rattling noise. If your MacBook is working otherwise, do not lose any sleep over it.