Sanhedrin 5: Eggs, Marsh Water, and Halakhic Leadership (Oh my!)
For a judge to not undertake financial responsibility for an error in judgement, he needs permission to judge from the exilarch. Plus, complications between the authority granted by the exilarch in Babylonia and that granted by the nasi in the land of Israel. Plus, the origins of the terms of rabbinic ordination of different levels, even (mostly) to this very day. Also, a focus on the authority of establishing (and permitting) the status of the first-born animals. Plus, some dramatic errors and what happened afterwards, for example, in the liquids that would purify or render impure (or do nothing). Also, the greatness of Rabbi Yehudah HaNasi in recognizing the significance of making halakhic decisions.