As noted, the "duck test" for telling an employee from a contractor is Section 6 of the Employment Relations Act 2000 as applied in Bryson vs Three Foot Six Ltd.
The Employment Relations (Film Production Work) Amendment Bill (or the "Hobbit Bill requested by Sir Peter Jackson and Warner Bros") is now the law. It stops the "duck test" being applied in the NZ film production industry.
The facts of your employment, as in Bryson's case, are no longer relevant. In the NZ film production industry, you are a contractor (with no security, no sick pay, no ACC, no holiday pay) unless you have a written contract of employment stating that you are an employee. As from today, on any Jackson/Weta film production, being an employee is at the whim of Sirs Peter and Richard.
The Three Foot Six practices of issuing detailed contracts of employment that use the word "contractor" instead of "employee", and issuing pay slips marked "invoice", will be conclusive proof of the fact that you have no rights as an employee.