El Rubius had a 3 hour look at the game and apparently this came out (according to Reddit):
He said he watched Rob Nelson, Rockstar's head of development, shoot an NPC in the head with a shotgun, and the head flew off completely—so much so that he wasn't even sure if this level of gore would make it into the final version of the game.
He mentioned that you can hide bodies inside car trunks, just as Jason and Lucia can climb into the trunks and hide inside them.
Rob Nelson took the Lucia and Jason characters to a fully explorable hotel and wandered through the lobby with them, using the elevator to reach the roof without a loading screen—and by chance, there was a helicopter there, so they stole it.
You can rob jewelry stores outside of story missions, and the 3D map showed that one of the stores contains loot valued between $15,000 and $40,000, as well as revealing entry points that can be used to plan the heist.
Nelson rifled through an employee's desk, where they found the safe code and opened it, and they had to pick up every gold bar and every diamond and every stack of cash one by one—even the cash registers at gas stations are emptied bill by bill.
"Rubius" says that one of the techs at Rockstar told him the map is about 3 times larger than the Red Dead Redemption 2 map, and he saw the map for a brief moment and says it looked like an island without the northern section that's been the subject of rumors.
The version "Rubius" saw didn't include first-person perspective, and Rob told him that the perspective hasn't been added "at the moment," which means this could still change before release.
After Lucia took off in the stolen helicopter, Jason sent her a text message saying, "Hey, aren't you forgetting something?"—after she left him behind following a heist.
Leaving Jason or Lucia behind during a shootout might make them mad at you, and "Rubius" says their relationship with each other can later affect how cooperative and efficient they are during heists.
A man stopped them dead in the street and begged them to drive him home and help him, which led to the start of a mission involving a reward and a cinematic scene.
Players can ride electric scooters and kick pedestrians while moving, and in cars, Jason can suddenly open the driver's door to hit people or other vehicles.
You can ask dog owners for permission to pet their dogs, but some dog owners or the dogs themselves might refuse, and "Rubius" saw Jason's arm actually pushing toward the leash of one of the dogs as he passed by it.
Beach crowds change depending on the time of day, just as character footprints form in the sand, and small objects like phones and glasses fly off when NPCs get hit.