In at least one questions ( How to compute molecular formula?) there is broken formatting, but only in the posted form. The preview view (if one were to try and edit it) shows what I believe is the correct output.
Text for the line in question:
WCl$_{6}$, WCl$_{14}$, WCl$_{18}$, and WCl$_{21}$.
How it is displayed on the site:
How it is previewed:
This appears to be a bug.