From what I gathered from last week's leaked footage:
Banner eventually becomes Dr. Hulk at the Avengers facility.
Dr. Hulk and Rocket finds Thor is fat and Korg and Miek from Thor Ragnarok lives with him on another planet.
Stark finds Rocket working on the ship at the Avengers facility while Doom and Gloom from The Rolling Stones is played in the background. Fat Thor is wearing sunglasses indoors and Stark refers to him as Lebowski.
The walking scene in the Avengers facility is real with Fat Thor and Dr. Hulk wearing the white Avengers' suits.
Dr. Hulk, Captain America, Iron Man, and Ant-Man went back in time or an alternate universe to the Battle of New York in 2012, finds old Hulk going ape crazy.
Captain America fighting his old previous self.
Dr. Hulk wears a Stark made Infinity Gauntlet with the Infinity Stones already inside it but it is too powerful for him to wield it.
Fat Thor, Iron Man, and Captain America fighting Thanos on a different planet with Captain America wielding the Mjolnir and his shield.
Captain America hears Falcon's voice through radio and was told to turn around, Okoye, Black Panther, and Shuri came out from a big portal.
Everyone who had died in Infinity War are back with Captain America calling out Avengers Assemble into an all out war against Thanos. This scene resembles the Battle at the Black Gate from Lord of the Rings Return of the King.
Spider-Man and Iron Man hugging it out. Captain Marvel destroys Thanos' giant ship with one blast.
Spider-Man finds the Infinity Gauntlet and gives it to Captain Marvel who has a new hairstyle.