iFixit has already divorced, the new Mac mini apart and you can see pictures here.
The new Mac mini from Apple has a so-called unibody aluminum design which means that it is more robust and completely different design than the previous model.
At the bottom is it possible to remove a cover and get to including RAM and fan.
You must be a little further into the machine itself if you have to change the hard disk.
You can see pictures with a lot of information from iFixit.