Lots of different interesting stuff. The reason why the Trident ended up like it did is that it was mostly an after thought, they put it in because various monsters used it.
And they thought of making it do straight up 1d8 damage, but felt that would make it the best thrown weapon in the game, so they decided that the least disruptive way to deal with how the elements of the Trident interact was to just leave it like the spear.
Also the way Ranger Alternate class features and subclasses interact was interesting. Like if you take the animal companion subclass and feature you get pick a higher CR animal, if instead go Gloom Stalker and Beast Companion Alternate feature, which causes issues with the Gloomstalkers bonus spells know which normally would be useless if you traded your spells for a companion was to allow you to cast each of the bonus spells known once per long rest without slots. I really liked it.
And of course the Great Weapon fighter seems to be progressing well.
Oh and a Whirling Blade Fighting style was shown, only wear light or no armour and you can use two weapon attack without expending your bonus action, and you get ability mod to off hand damage.
He also explained the math of replacing spell slots with a none spell slof class feature. For thr beast companion class alternate feature, the Beast Companion for example make it's attacks without using your action, and eventually get more hit dice as it levels.
