Definitely one of those chapters that is remembered for years.
Biggest surprise for me is definitely that Oda gave us even a little information before the Golden Week break. I thought for sure it would be delayed until after the break next week.
Other than that little joke I think the biggest thing is that the history of the Ancient Kingdom and Void Century might be more complicated than what I thought. There might be some reason behind the madness and cartoon evil of the Celestial Dragons. Will have to see after the break what other context we get.
Also, just in case it wasn't obvious Vegapunk definitely knows about Imu. That reference to him and the Elders' reactions to that made it clear. So hopefully we get some information on him as well.