The first trailer for Spider-Man: Across the Spider-Verse has been revealed, and it contains a ton of easter eggs and small details that reference the first film and others from Sony Pictures Animation.
One of the first easter eggs that can be spotted in the trailer happens within the first few seconds. Despite looking a little bit older than he did in the first Spider-Verse, the opening shot is the same as the ending shot from that film, including having Miles listen to Sunflower by Post Malone.
Next, as the portal to another dimension opens up, you can see several items start to float around Miles. The first of these is a "true-life tales of Spider-Man" comic book featuring Miles Morales, implying that he's getting comics made about him similarly to the ones that he read about Peter Parker when he discovered his powers. The cover says, "Saved the multiverse... now what?".
After this, you can also see a picture of Miles and Uncle Aaron floating around him as Gwen Stacey sits down on his bed. You'll also notice that Gwen is wearing a wristwatch similar to what Miguel O'Hara was wearing in the Spider-Verse post-credits scene, implying that she's figured out how to traverse dimensions through the same technology.
The next easter egg was actually pointed out by the Sony Pictures Animation Twitter account. As Miles starts throwing toys out of the door and Gwen looks at a shelf, you can see Katie's moose from The Mitchells vs the Machines, the most recent film from Sony Pictures Animation. From one legend to another.
For our next easter egg, we've got a two-parter. When Gwen looks at Miles' sketchbook, on the left-hand side you can see the Hudson Valley bus ticket from when he and Peter went to visit the Alchemax Lab. The picture of Gwen Stacey that Miles has drawn also looks like it's from her introduction in that scene.
In the next scene, we see Miles travelling to another dimension. As we pointed out before, this appears to be a futuristic India thanks to the Hindi text seen throughout the world, which means that this could be the universe of Spider-Man: India, aka, Pavitra Prabhakar. We also see Miles do the same spinning swing stance he did when learning web-swinging from Peter in the Hudson Valley.
The final easter egg of the trailer can be seen when Miguel grabs Miles. You can see the number "928" when he uses his dimension-hopping device, which likely means Earth-928, Spider-Man 2099's universe. That means he's taking Miles to his own dimension.