What is That Circular Device?
The official Infinity War trailer introduces us to some kind of giant circular device hovering above the city. It causes Peter Parker's Spider-Sense to tingle, and we see Thor and Spider-Man trying to destroy it. We don't know exactly what this device is, or what it's called, but the SDCC/D23 footage offered a few more clues as to its purpose.
We see that the device is activating, and in previous footage we see the destroyed device falling down to Earth and the smoldering debris left on the ground. One theory that could explain this device is that it is a portal, similar to the one Erik Selvig created in the first Avengers film that brought in the Chitauri invasion. This one is just more secure.
Given the heroes' apparent desperation to the destroy this thing, it's likely that the invading forces seen in the trailer come out of this device, or others just like it.
What Happens to the Vision?
Everyone knows that the Vision is in big trouble, considering Thanos is gathering Infinity Stones and he has the Mind Stone embedded in his head. In the trailer, we see just how painful it is when Thanos and his people come to collect their prize. Whether or not Vision ultimately dies, the SDCC/D23 footage gives us slightly more to go on regarding his Infinity War arc.
In the previous version of the trailer, there is a quick shot of the Vision locked behind bars. What this means has yet to be seen, but we can make a few guesses for now. Considering that Wanda is mostly shown with or peripheral to scenes with the Vision, it isn't hard to believe that their relationship will be greatly affected by the events of the film.
With the idea of Vision in jail, and then having the Mind Stone pried off of him, it can be theorized that Wanda will either be attempting to protect him from Thanos or, given the quick shots that show her fighting in the streets, she is trying to save his life.
The Might of Thanos
We know from the trailer that Thanos will be in possession of at least the Power Stone and the Space Stone at some point in the film. While there are still several others to gather, he still manages to display an amazing amount of power. He can clearly teleport and knocks Iron Man out with one punch, but the SDCC/D23 footage gives us a little more.
At the end of the early trailer, we see Thanos use the Infinity Gauntlet to capture some kind of space debris and hurl it down from the heavens, no doubt causing plenty of destruction on the Earth below. Just imagine what he can do with more than two stones.
The Death of Spider-Man?
Missing form this trailer is a scene in the SDCC/D23 trailer where a maskless Peter Parker is clearly injured and apologizing to Tony Stark by his side, and it's completely possible that he's lying there dying.
Stick with us for a minute...
In the official trailer, there's a scene where Thanos violently attacks Spider-Man and slams him into the ground. Could this lead to his death? It would explain why Tony Stark seems to be so defeated in the shots where he is out of costume. He's sitting down crying in one shot and walks out on the other heroes in another. Stark is clearly defeated, and it could be Peter's death that ultimately destroys his will to carry on.
Of course, while some fans would love to see Peter ushered off into the hereafter with Miles Morales taking his place, Sony has not indicated that this is in the cards. Tom Holland is contracted for several more Spider-Man films, after all, and there's the matter of a fourth Avengers film that leads directly into the solo Spidey sequel. That said, he could still die in Infinity War's final act... before being reborn in the next film thanks to the powers of a full-functional Infinity Gauntlet.
Directed by Joe and Anthony Russo, Marvel’s Avengers: Infinity War stars Robert Downey Jr., Josh Brolin, Mark Ruffalo, Tom Hiddleston, Chris Evans, Chris Hemsworth, Jeremy Renner, Chris Pratt, Elizabeth Olsen, Sebastian Stan, Benedict Cumberbatch, Paul Bettany, Samuel L. Jackson, Cobie Smulders, Benedict Wong, Zoe Saldana, Karen Gillan, Vin Diesel, Dave Bautista, Pom Klementieff, Scarlett Johansson, Tom Holland and Anthony Mackie. The film opens May 4, 2018.