Today, University of Canterbury Criminologist, Professor Greg Newbold said changing the money in Hong Kong would be a "safe bet", provided you knew what you were doing.
The easiest way would be to launder the money, as it would be unsafe to change it through a bank, he said.
"They won't be able to change it legally. No one will be able to go into a Hong Kong bank... the bank, highly likely, would notify the authorities, you would be taking a risk. Unless you had some corrupt official inside the bank. Then that could happen.
"There are high levels of corruption in Hong Kong so it depends on whether you are dealing with a corrupt official or a dedicated official. I think if you've got $1 million anyone can be corrupt if you pay them."
The best bet for a person with a large amount of cash would be to launder it through purchasing drugs, or even real estate, Mr Newbold said.
"For example, you could buy some estate or some property worth $500,000 and say, 'listen I'll give you $1 million NZD no questions asked'."
The money could also be laundered through gambling, as a casino would exchange chips for New Zealand dollars, he said.
"You wouldn't need to necessarily spend the $1 million altogether, you would drip it out here and there, a few thousand here and there over a few years.
"It would be pretty easy to do that really, in fact you would have to be unlucky or silly to get caught I would think."
The stolen cash was being transported to the Bank of China in bags labelled G4S International Logistics in a luggage box through a cargo transfer service provided by a Cathay subsidiary, Hong Kong Airport Services.
Surveillance footage showed the three bags fell out from the trailer, which was not properly fastened, while it was making a turn at a corner, Shanghaiist said.
"During the transfer, there was only a driver on board without a security guard. Only 10 minutes later when the cargo arrived at the station, the driver realised the bags were missing."
Two of the three missing bags were later found on the tarmac, but the third remains missing.
A Cathay Pacific spokeswoman confirmed the airline had transported the "valuable shipment" on July 17.
"Upon arrival it was transferred to the cargo terminal where part of the cargo shipment was found missing," she said.
"As the case is under police investigation, we are unable to provide further details."
G4S International Logistics - which specialises in transporting valuable cargo - denied responsibility for the lost money, which is insured.
G4S North Asia commodities director Janet Leung told the South China Morning Post that the entire currency consignment was
"accounted for" prior to its transfer into a restricted area at the airport. She was "very concerned" by the loss.
"This loss occurred within the controlled airside sector of HKIA - a restricted area that we are not allowed access to," she said.
"We can confirm that the missing banknotes were safe and accounted for during the entire time it was in G4Si's possession, up until it was in the controlled airside sector."
The security group was "confident" the police and airport would be "diligent in their investigation and recovery efforts", Ms Leung said.
"G4Si is working hard to understand the chain of events that led to this loss," she said.
Hong Kong police were investigating the theft. Police in New Zealand said they were aware of the theft but were not investigating it.
A spokeswoman for Auckland Airport could not comment.
A Customs spokeswoman said the agency was not involved in the incident.
- With additional reporting from NZME News Service
