Vaguely related to:
Links to URLs containing parentheses
This is likely to do with encoding URLs for safety, but here's a case that works in the preview and the rollover title is "Speakers" yet breaks when posted:
[Boston Dev Days] : http://stackoverflow.carsonified.com/events/boston/(Speakers)
The outcome looks like this: Boston Dev Days
While the preview looks like this: Boston Dev Days
If you haven't yet spotted the difference, please mouse over each link above.
It is proper to put a space between the url and the parenthesis, but the preview accepts the improper format.
I might note this is a preview bug.
The preview will lead you to think that the format shown is a correct way of adding a comment/title to a url. It is not.
Also breaks if you use [multiple words] yet shows in the preview fine. And lastly, if you make a code block like the one I just made, then use control-L to link a word later on, the url number for
 which should have been the "outcome" line, becomes
 remains assigned as it was, but is mistakenly assigned to the non-linked text in the code block.
Clearly these are minor, but it's worth noting for completeness.