This originally was posted here. The version below has been slightly abbreviated. See the original for more images.
After several teasers this past week, the new Justice League trailer is finally here. There's a lot happening, and we see the team coming together to face a deadly threat. Here's everything that's going on in the trailer.

The trailer starts out with Bruce Wayne traveling the world to find the various superheroes to recruit them for an upcoming battle. For a guy who devotes a lot of money and Bat-Vehicles to fighting crime, he takes a more subdued approach to seeking out allies.
We hear Bruce mention an attack is coming, but Wonder Woman disagrees: "It's already here."

In what appears to be Silas Stone's home, a Mother Box has been activated. Silas is Victor Stone's father. He was seen in the video footage Bruce Wayne found in Batman v. Superman: Dawn of Justice.
As Silas sees the Mother Box has been activated, a Parademon rises behind him. Parademons were seen in Bruce Wayne's future vision/dream. They are Darkseid's troopers on Apokolips.

Arthur Curry, aka Aquaman, rescues what appears to be a fisherman. We can assume he was rescued from the rough seas and Aquaman didn't sink his boat. In the previous footage shown at last year's San Diego Comic-Con, Bruce arrives at the tavern seeking Aquaman out. Perhaps that scene takes place right after this.

Cyborg is shown in action. It's not clear how long it's been since his transformation. He is using his abilities to help others. That should make him easier for Bruce Wayne to find.

The trailer shifts to showing the Flash in action. We can expect a lot of flashy visuals with the Speed Force. In a more abbreviated scene than what was shown in last year's footage, Bruce throws a Batarang at Barry Allen in order to get him to reveal he's the Flash after he tries denying it.

Batman is finally shown in action. In the middle of a battle, Batman swings into a Parademon, dodging lasers being fired at him.

Aquaman makes a giant leap in order to throw his trident at some Parademons.
During this scene, Wonder Woman tells Bruce, "They said the age of heroes would never come again." It's not clear what or who this is referring to. Were there other heroes? Were there other heroes in this cinematic universe before now? Perhaps we'll find out more in the Wonder Woman movie.

Aside from being half machine, Cyborg is also able to fly. He can also cover up the exposed parts of his face.

Some viewers have critiqued the DC movies as being too serious. There will be humor in the movie. Barry asks Bruce what his superpowers are. Bruce replies, "I'm rich." This also sets the scene to reveal Batman's new vehicles.

Lois Lane makes an appearance. From Batman v. Superman, we know Superman is unable to take part in the action--at least for now.

Mera, Aquaman's wife in the comics, is seen underwater. It's not clear how much of Atlantis we'll see in the movie.

Barry Allen is visiting his father, Henry, in prison. Similar to the comics and TV show, Henry must have been arrested when Barry's mother was killed by Reverse Flash. This is something that would be fleshed out in the solo Flash film.

A horde of Parademons is attacking. It looks like either the battle has arrived on Themyscira, Wonder Woman's home island, or the Amazons have joined in the fight elsewhere.

Batman meets up with Commissioner Gordon, who comments, "It's good to see you playing well with others again." We know Batman's been active in Gotham for years and that his partner, Robin, was killed. Aquaman arrives when Batman and the Commissioner are speaking. His comment towards Batman's outfit further shows there will be some humor. Batman and Aquaman may not be getting along too well.

Despite any differences Batman and Aquaman may have, they will be fighting side-by-side. Aquaman posed on top of the speeding Batmobile also further illustrates his brash and reckless behavior. Aquaman here is a warrior that seems to enjoy a good fight.
Justice League arrives in theaters on November 17.