The Mishnah commits to writing the Jewish wisdom that had previously been passed down orally. It's broken down into 523 chapters. How many of these chapters contain a dispute of Jewish law (aka, a halchic dispute)?
The answer: 522! All but one of them.
I found this out while scanning my copy of Art Scroll Interlinear Sabbath & Festivals Siddur. Unfortunately, I wasn't able to verify this little factoid on the web. But here's a snapshot of the commentary:
The relevant text:
Chapter 5 of Zevachim was chosen for three reasons: (a) it discusses all the sacrifices; (b) it was the only chapter in the Mishnah in which there is no halachic dispute; and (c) its text is of very ancient origin, possibly even from the days of Moses.
In other words: get three Jews in a room and you'll have four opinions.
And why not? It's tradition!