Ultron returns to cause even more trouble for the heroes in another trailer for Marvel's "Avengers: Age of Ultron." (Walt Disney Pictures)

Marvel Studios provides another peek at what could be the superhero movie of the summer (apologies, Ant-Man), and one thing is clear after two “Avengers: Age of Ultron” trailers: Nothing is certain.

The stability of the team doesn’t look good (everyone is arguing). Iron Man might be the cause of all the drama (Thor, Captain America, Hulk — so many Avengers aren’t happy with him). And Ultron seems all but unstoppable. The good guys may win here, but at what cost?

Here are Comic Riffs’ 5 Takeaways from the new trailer for “Avengers: Age of Ultron,” which hits theaters in May:

1. There’s something more powerful than the Avengers

The Avengers are clearly outmatched — a fact that’s affecting the team. We’ve seen the scene in both trailers in which Thor lifts an armor-less Tony Stark by the throat. This time we hear Thor’s voice telling us (and Tony) that Ultron might present the first time in Stark’s life that he doesn’t have the answers to everything. It’s going to take the combined might of Earth’s mightiest heroes to stand a chance against Ultron, but it is not looking as though they’ll be a team by the end of this movie.

2. The twins remain a mystery still

After two Avengers trailers, we still have seen very little of “the twins” that we saw at the Easter-egg ending of “Captain America: The Winter Soldier.” Quicksilver and the Scarlet Witch remain a mystery that isn’t any closer to being solved. We get a few glimpses of them. Friends? Foes? Inhumans? (We know they can’t be mutants since Fox owns the rights to the X-Men.) Whose side are they on?

In the first trailer, it seemed as if they were with Ultron. This trailer gave no hints. “Age of Ultron” is shaping up to be an event that will have Avengers choosing sides. What side will the twins be on?

3. Is that Wakanda?

Andy Serkis may well portray Ulysses Klaw, who happens to be a future villain of the Black Panther (who we now know is going to be played by Chadwick Boseman). For an instant in this trailer, we see a woman, in a cave, looking to be heading toward a body of water. If you blinked, you missed it — but just where is this cave? Ultron seems to have built quite the body of metal. And what place in the Marvel universe happens to have the strongest, most indestructible metal in the universe? You guessed it: Wakanda. Could the first glimpse of the Black Panther actually be in this Avengers sequel?

4. Hulkbuster makes the Hulk very angry

We saw the Hulkbuster armor for the first time in the first “Age of Ultron” trailer. This time, we see an extended round of that fight. Has the Hulk ever looked angrier? Tony has no trouble throwing around the strongest there is in the Marvel universe, but the Hulk gets in a few kicks and punches, as well. Will other Avengers choose sides? Given that a Civil War movie is coming to the Marvel movie universe, is it going to be Iron Man vs. everyone?

5. He’s going to tear the Avengers apart

Ultron is a double threat to the Avengers. His presence, and the fact that they may not have the manpower to stop him, is already causing drama within the team. He’s breaking down the Avengers psychologically while also possessing the strength to take on the team by himself (although he has many a robot helper). Even if the Avengers can find a way to take down Ultron, he may succeed in destroying the team as we know it. The Avengers might survive the physical test — but what about the emotional one?