The clock was ticking: It was the second year of production on Richard Linklater’s Boyhood. Ethan Hawke, who had been filming Assault on Precinct 13 in Canada, had managed to get a few days off from that film, so he’d headed down to Austin, Texas, to shoot a sequence in Boyhood in which Mason Sr. — the divorced dad he plays — takes his kids, Mason Jr. and his big sister, Samantha, on an outing to a bowling alley. It was just one small, serendipitous moment in a marathon of a sporadic movie shoots whose 39 filming days stretched from 2002 all the way through 2013.