Gangster Squad (R) Sometimes perfectly dumb, perfectly fun and perfectly entertaining scripts get grabbed up by directors who think they are making serious films. That’s what seems to have happened with Ruben Fleischer’s Gangster Squad, a ’40s gangster flick that had the potential to be — and I mean this in the best possible sense — dumb entertainment. However, any possible amusement value got sucked from it by derivative style and an uneven, too serious tone that betrays its true junky heart. Here, we have a movie with a solidly contrived B-movie premise about a group of hardass L.A. cops taking on real-life mobster Mickey Cohen (Sean Penn) vigilante style. Fleischer, unfortunately, has decided his best bet is to ape a whole slew of other people’s gangster films — notably Scorsese and De Palma — while packaging it inside occasional and cheap approximations of Guy Ritchie’s visual style. So much of the film feels listless and lazy. And the crudely lit interior and night shots make the film’s digital photography feel chintzy and visually flat (and a whole lot like a daytime soap). This would be perfectly suitable as a trashy work of overheated, hard-boiled pulp. Gangster Squad suffers from the Christopher Nolan syndrome of taking inherently light, preposterous fodder and attempting to gussy it up into something seemingly weightier. What’s left is a movie that’s not entertaining, energetic, enlightening, or anywhere close to good.