Unfortunately, this is a known issue with Facebook's Javascript libraries. In October, they marked the problem as "Fixed waiting testing", and hopefully it will be pushed out soon. To our knowledge, you shouldn't be seeing any 'real' links that point these types of URLs. Google Analytics picks up on them because of how the page renders, which is where most people notice them, but on Facebook.com (if a link is shared) or in other locations, the link should not contain the fb_xd_fragment.
For more information on this issue, check out the post below:
www.sourcecoast.com/forums/topic?id=1431&p=1#p5732 
Inbound URL from Facebook breaks the site
