Ultimates2 is bugging me recently simply because I don't read Marvel "events" anymore, and so there's stuff going on here that I missed out on.
One thing specifically that's been bothering me is that if the Earth is surrounded by this impenetrable dome, and our heroes can't get back in; why are they working so hard to keep the Chituari away from it?
Also, does anyone else feel like Maker & High Evolutionary just kind of "appeared" without any rhyme or reason? I'm not sure why they are there, aside from Maker's throw-away line about Molecule Man asking him to get involved...
The situation with the shield and Chituari is from Secret Empire and only appears in the Ultimates via a Secret Empire tie in issue. The Chituari are attacking everything their path which forces the heroes to fight. Plus, if the Chituari are able to breach the shield, they will unleash death and destruction on humanity.
Ewing features Maker in his New Avengers run, so those who read that book would not perceive Maker as popping out of nowhere.