I noticed a bug in MediaWiki's MathJax implementation:
When using "\ " to produce some spacing at the end of a formula this only works in front of e.g. dots or commas, but not in front of colons, semicolons or exclamation marks (those were the cases I tested)
Examples (NOT working):
I tested these TeX commands in LaTeX as well as the online demo of MathJax and it works in both of them, so it seems to be a problem in MediaWiki's implementation of MathJax (or only solved recently in MathJax itself, so the fix didn't make it yet into MediaWiki's code, English Wikipedia is using version 1.22wmf5 (43f93b2) at the time of this writing).