That was a fun episode, even though it didn't stray too much from the scope provided by the manga chapter like people have been hoping would happen. I'll second the notion that all the vibrant color was a really nice break from all the nighttime scenes; I remember feeling so much relief back in the day when Thriller Bark ended and I didn't have to look at that washed-out purple pallette filter any more. The Onigashima part of the arc was nowhere near as bad as that of course, but still.
Ryokugyu's voice was much higher than I was expecting. I didn't expect it to be as deep as Vergo's, which was about as deep as Junichi Suwabe goes, but I was still imagining something closer to that end of the spectrum. It makes Ryokugyu sound very youthful compared to the other Admirals, which is a little disarming, but the bounciness of his tone is probably close to what Keiji Fujiwara's take would've been past his few lines during the Reverie if he were still alive.
I wouldn't be shocked if that teacher in the classroom scene is supposed to be a caricature of a Japanese celebrity. His portrayal felt a little too specific to not be an impersonation.