Oscar-winning screenwriters of “The Descendants,” Nat Faxon and Jim Rash, moved the production of their directorial debut, “The Way, Way Back,” back to Duxbury on Wednesday. The directors, who have small roles in the film, have spent much of July shooting scenes for the film at Water Wizz in Wareham. On Wednesday, they were around Duxbury’s Powder Point Bridge. Liam James, who stars in the film, was spotted working on scenes with his young costar, River Alexander. James plays a boy who’s coping with family issues while working at a water park. Toni Collette stars as the boy’s mother. Collette’s boyfriend will be played by local guy Steve Carell, who will film much of this movie near his real-life family’s store in Marshfield. James has a recurring role on AMC’s “The Killing.”