OK, so what is happening is the review defaults into working through materials using an SRS algorithm. But if it is asked to come up with 5 questions for an automatic review and runs out of material halfway through, it will grab some random content from the lessons we have done with a flailing stab-in-the-dark guess at your appropriate level. It does this because it doesn't want to deliberately interrupt the SRS scheduling of the other words and doesn't have anything else for you.

http://popupchinese.com/account/review

It is possible to turn off this functionality by disabling the automatic review completely. That said, it isn't really a horrible thing to have random vocab thrust your way every now and then, which is why we have the system working this way. The alternate is either: (1) screwing up the SRS scheduling, or (2) changing the way the popup review works.

That said, I'll look into the pinyin issue with 聋. This problem *will* happen for characters with multiple pronunciations (since we do a sanity check), but in this case it may be that someone added it as a correct entry and it hasn't been reviewed and rejected yet. Not sure until I see what is happening in the database....