Now that the 'First posts' and 'Help & improvement' review queues have been retired, they don't appear in the list of the review queues in the top bar, nor do they appear in the /review page.
However, the pages are still active via /review/first-posts and /review/helper respectively - presumably to allow users to see their stats on them (my links point to Stack Overflow's review pages, but the behaviour is the same on all* Stack Exchange sites).
On the pages, instead of a notice saying that the queues have been retired, there is a confusing message:
Reputation is stored as a signed 32 bit integer, so presumably the exact required reputation is 2^31 - 1 == 2,147,483,647.
Instead of having the message says that I need 2147.5m reputation, perhaps the message should say, e.g.
This review queue has been retired.
or something similar - in addition to having the "Retired" indicator next to the review queue's name.
* Based on a sample size of 3 sites: Stack Overflow, Meta Stack Exchange, and Super User.