“Inspired by true events” claims the opening cards, but Gangster Squad bears much more in relation to other films in the genre than reality itself. Inhabiting this world of overblown clichés and marketable simulacra is a cast of caricatures spouting exposition for near 2 hours. There’s some enjoyable violence on show, and not all the set pieces are as bad as the climax, but the chief irritation is that this flick actually asks you to invest in its shoe-horned beats of formula. Here’s my stock tip: sell, sell, sell.