If the correct roll-over procedure drills had been carried out at the time of the accident, it was likely Private Mila would not have been killed, it said.
The findings stated Private Mila was not wearing a gunner's harness designed to stop him being thrown out of the turret in the event of an accident, as the Humvee hadn't been fitted with one.
"The existence and purpose of Humvee gunner harnesses was virtually unknown to personnel prior to this accident".
The court said the accident happened when the road narrowed significantly and developed a slope on its right hand edge tipping the driver down a slippery slope to the left of the road.
Its findings said some of the injuries sustained by other soldiers in the vehicle could have been avoided if they had been wearing seatbelts.
One recommendation ordered an investigation into the safety case for using seatbelts in Humvees.
Another said all NZ Defence Force Humvees should be fitted with gunner's harnesses.
A Defence Force statement said gunner's harnesses had not been used by the New Zealand Provincial Reconstruction Team for some time when the accident happened.
Commander Joint Forces New Zealand, Major General Dave Gawn said a number of changes had been implemented in the wake of the inquiry.
"Vehicle roll-over training is conducted for all personnel deploying to operate in vehicles in Afghanistan.
"Gunner harnesses are now used by all New Zealand gunners operating in Humvees.
"Further examination of possible improvements to pre-deployment training in New Zealand and training in-theatre has also been undertaken."
Mr Gawn said the vehicle driver had faced a "dramatic and unforeseeable change" in road conditions which could not reasonably have been predicted.
He said the resulting slide and the rollover was accidental and unrecoverable.
Private Mila was a good, professional soldier and his death was distressing for his family and fellow soldiers, he said.
"He was a popular member of his battalion and was well known as a colourful character. It has been a very difficult time for Kirifi's family as well as his comrades in the Defence Force."