"We're going to chop up her hair ... We've had to warn her school back in The States that she'll be looking a bit strange when she comes back," Mr Potts said.
Mr Potts said he had chosen Northland - with most scenes based at private property at Whakapara - as he needed somewhere "quiet, with good scenery".
The film-makers, who include Kiwi Mig Alves, recruited hundreds of Northlanders as extras for the shoot, who would be turning up over the next week.
The stage of filming currently underway is a test shoot. The movie's Chinese funders want to see how filming progresses before committing to a fully-funded shoot, which will also be in Northland.