I found the following error on the question review page. To reproduce it, click on the filter link. This happens on every type of review.
Edit: Idem for meta.
This occurs when the explanation of the type review has been collapsed (by clicking less) or there are no items to review for that particular category.
Browser: Safari; Chrome; Opera (I haven’t checked any other, but I suspect it’s similar.)
OS: Mac OS X (10.6.8)