md5 command inside of .mpkg directories?

Hello.

I found out that .mpkg is actually directory and not a file. Is that correct? I was using Mac OS X 10.7.4's Terminal's md5 command to compare files until it said .mpkg was a directory. I also cannot seem to find a way to make it MD5 recursively. Is there a way to do this? I am basically comparing a burned CD files and my local copies.

Thank you in advance. 🙂