This wiki previously had the DollarSign extension installed, which allowed for math to be enclosed between "$" instead of the usual <math>...</math>. To get a "$" we instead used "\$".
This caused problems with the search results page: at the top, the "you searched for..." notification was garbled because somehow (perhaps a double quote instead of a single quote in the wiki code) the notification was displaying math mode. This was fixed by searching for the notification in Special:AllMessages and adding "\" in front of all "$".
Now that this feature is no longer active, this will need to be changed back. Also, there are some pages where the dollar sign was used, and these will need to be changed. If you spot one and have the time, please fix it, or alert Oscar Levin.
There is a quick way to get math mode: enclose the formula in <m>...</m>.