I can't get enough of this series. Unfortunately, it seems like there are some pages missing at the end, as it stops right in the middle of a key plot element. And there are no pages that you would typically find at the back, like the obligatory "Stop! you are reading the wrong way" page. It's thinner than the other volumes, also.

Has anyone else gotten a copy like this, or is mine a rare mistake?

If your copy doesn't have translation notes, ads for other manga, and a "The End: You're Reading the Wrong Way" page at the very end, then it sounds like you have a copy with missing pages as that's a definitely printing error. If you purchased it from a bookstore, please try to return it for another copy.

Yep, it's missing those. I just went through Amazon's return process, which was pretty easy and simple to do. I'll just think of it as an extra cliffhanger

Oh wow. I will need to check mine. I don't even remember where I bought it from. haha