While each passenger goes through a number of strict checks - including having their name checked against international fugitives and "banned flyers" lists - the vast Interpol database that holds information on stolen passports is only checked when an individual is considered a "concern".
There is still no trace of the jetliner, which disappeared from radar on Saturday with 239 people aboard while flying from Kuala Lumpur to Beijing.
But the search area has been expanded and Malaysia Airlines says the western coast of the country is now the focus of the hunt.
Despite automatic checks with Interpol not being made, Karen Urwin, Immigration New Zealand's Manager for Border Operations, told the Herald she was "pretty confident" that if the passengers on the Malaysia Airlines flight had tried to come here, they would have never been allowed on the plane.
"If those two were trying to get on to a flight into New Zealand we almost certainly would have pinged them through all those other red flags around how their travel was booked, who booked it, their bizarre travel route ...
"There's all those flags and we would have intercepted them at check-in and chances are we would have offloaded them."
She said New Zealand was a world leader in many aspects of border control, but some countries didn't have the luxury of the sophisticated systems used here, such as the advanced passenger processing (APP) system.
"If you don't have systems running behind it and those teams of highly skilled, highly trained senior Immigration officers doing that profiling; not everyone has that luxury like we do, so no - those two guys wouldn't have got past check-in, I'm pretty confident of that."
In some cases where the APP system flagged a possible security concern, Immigration did go into the Interpol lost and stolen database.
"We do have access to it but what we don't do is that automated match. The Interpol database is so enormous and is notoriously inaccurate.
"You would need the combined computing power of probably Nasa and the Pentagon to run that kind of data match [and] it would probably take you six hours to check in."
Last year 11 false passports were discovered at New Zealand airports, down from 34 in 2012 and 62 in 2011.
How advanced passenger processing works
* When you check in at an airport, you swipe your passport and your passport number and details are checked. Those details are transferred into Immigration New Zealand's database.
* It confirms whether you require a visa and any other requirements.
* At the same time another team is working in Auckland to profile all the flights that come into New Zealand. They check each passenger's name against databases, including no-fly lists.
* Anyone identified that causes concern is not allowed to board and Immigration NZ is called.
