Problems, problems, problems.
Basically, the moral of the story is: when you make a big, expensive studio movie call Cameron, Bay, Spielberg, Emmerich or Nolan. They'll get the job done and they'll keep things organized.
Take a look at this great article about the making of "World War Z". So many problems, it's crazy:
I like Pitt (and zombies) so I'm actually looking forward to that movie. Hopefully they'll be able to save it.