Someone also made a concise list of everything they noticed after watching all the footage
Map is located in Vice City (Miami) - looks huge, one video features a lake which IRL is quite far from Miami, perhaps the map features a bigger chunk of Florida
At least 2 protagonists, Lucia and Jason, switchable characters, looks like you can call them to help you e.g. when robbing places
New animations like prone, characters bracing in shootouts, an animation titled "overdose", animations referencing horses and horse riding
Redesigned weapons wheel with additional slots for cigarettes, medicine, trauma kit...
You can pick up/drop weapons, carry a duffel bag, looks like the weapon inventory will be more limited, lots of drug dealing references
Cars have interiors with lots of detail and animations - seat, mirror, wheel, sun visor adjustments...
Robbing shipping containers, drilling locks
Open interiors like motel, metro station, restaurants, pawn shop (selling stolen goods?), supermarket..., references of functional elevators
References of RPG elements - food, drink, sweat, fatigue, animal taming...
Mountain bike ramps references, city bikes renting
Car damage looks to be more detailed, only 1 proper collision in the leak afaik so hard to say
Boat damage tests - perhaps it will carry over from RDR2? Loved the physics there.
Cloth (skirt) physics
Cops remember your vehicle model/plate, I hope San Andreas' respray to escape is not making a comeback lol
Small robberies are full of detail, NPCs reacting to everything going on, cops surrounding the place without entering blindly
A list of dynamic world events like missing tourists