The book of Leviticus ends in chapter 27. And chapter 26. And chapter 23. And a bunch of other chapters going all the way back to chapter 1.
So what's up with all these false endings? Was Leviticus actually written by Peter Jackson?
Probably not. But there are a couple more historically grounded theories. Among those who believe that Moses himself wrote the whole book, the theory of unified authorship derives from the well-proven fact that it's impossible to keep anything straight while driving a caravan of bratty kids cross country. So it's a little all over the place, yeah. But we should cut Moses some slack.
Other scholars see the mix of beginnings, endings, and writing styles as proof of multiple authors writing different at different times. One thing on which the multiple-author scholars tend to agree on is that Leviticus was patched together from a bunch of old instructions for various rituals, mixed in with the priests' old waiting room copies of Sports Illustrated, Redbook and Field and Stream. The priests who put this stuff together then tried to make little fixes to make it sound like everything fit together in a single book.
As far as the number of authors goes, the exact number depends on whether scholars need something new to argue about at conferences. A particularly popular idea is that there were two main guys (or groups of guys) who did all the putting together.
The first guy put together chapters 1-16. The guy who did this is called P, from Priestly, because—well, look at it. It's like The Priest's Little Instruction Book. Then, starting in chapter 17, Leviticus starts talking a lot about "you have to do this because God is holy and you have to do that that because God is holy." The guy who cobbled this together and sprinkled in a bunch of holy talk is H, for Harold.
Just kidding. That's H for Holiness, and his Holiness Code rolls merrily along through chapter 26. That chapter ends after God threatens to take his football and go home if the Israelites keep acting like jerks. And then? Well, there's not really anything left to be said.
Oh wait. Chapter 27.
This last chapter (really, this time!) was probably tacked on afterward by priests who wanted to make sure that Leviticus left no wiggle room about how much the people have to give the priests. Or it could have been added in by H when he put everything together in one book. Who knows? (We sure don't.)