By: Addison Wylie Considering the talent involved, it’s hard to believe everyone agreed to star in a film this goofy and shallow.  Especially, by actors like Sean Penn, Ryan Gosling, and Josh Brolin who have recently been very selective about their work. Gangster Squad appears to have done its homework considering its 1940’s backdrop.  Its attractive period style, make-up and costuming convince us the film will have more weight to it since more effort is…