As of 5:26 AM on September 9, 2016 (UTC), the review queues went down:
My browser is reporting that this page is an HTTP Error 500 page, suggesting (as noted) that something is wrong with StackExchange's servers.
This bug can be reproduced by attempting to visit any of the review queues on the site.
Moderator Tools and flagging seems to be unaffected at this time.
