Wes Anderson’s films have always featured a kind of play-acting, from the cops-and-robbers shenanigans of Bottle Rocket to the spiritual tourism of The Darjeeling Limited, with his characters trying on different personas for size. Maybe that’s why Fantastic Mr. Fox, itself a new kind of persona, fits so clearly and cleverly into Anderson’s body of work, which helps make it such an unexpected joy from start to finish — the director’s best since Rushmore. A typically easygoing Anderson cast, anchored by a nicely understated George Clooney in the title role, inhabits a world of talking animals who are almost, but not quite, human. With a lo-fi stop-action style that well suits the Roald Dahl vibe plus an uncompromised deployment of the director’s stylistic trademarks, Mr. Fox simply follows that golden rule of great kids’ movies by declining to pander to anybody’s idea of what a kid should or shouldn’t find amusing. Helped along by a suitably droll screenplay, everyone involved exudes heaps of effortless cool — this film is the kind of suave you get when you’re having just huge amounts of fun.