“We may have to do it 22 times to make it look like you’ve done it a thousand times,” David Fincher told Todd McCarthy in 2010, describing his philosophy of drilling actors through many takes. There’s no such thing as a one-size-fits-all approach to filmmaking, but Fincher’s determined diligence leaps to mind while watching writer-director Kevin James Barry’s Serena and the Ratts, in which none of the actors appear confident carrying out the physical tasks — cocking a gun, brandishing a knife, strangling a target, even just talking on the phone — they’ve been assigned to perform. The movie’s absurd, non-chronological plot consists of a band of scientists (led by a devious professor, played by Jeremy Bates) that plans to create wormholes in order to travel back in time and assassinate a pre-Nazi Party Adolf Hitler. In turn, contract-killer Serena (Evalena Marie, rocking a Jessica Chastain–in-Mama look) is brought out of jaded, PBR-flavored solitude by her crafty mentor (Jonathan Thomson) to stop the murder and prevent the repercussions that such an act would have on history. (Serena’s live-in co-worker/companion flimsily explains this reasoning as follows: “If Hitler never happened, then somebody else would’ve done the same thing. Somebody more successful.”) This time-warping premise leads to scattershot action sequences and bland speculation — “What if time is like a record?” Serena asks — that makes one appreciate all the more the balance of genre excitement and abstract thinking present in James Ward Byrkit’s recent, similarly low-budget Coherence. But first things first: An actor who isn’t convincingly smoking a cigarette on-screen certainly can’t be expected to pontificate on the meaning of time.