One passenger, who did not want to be named, said he was sitting in the back row of the plane on the flight so was unaware of any trouble.
However, on reading the Herald on Sunday report in to the incident, he said it was unsettling to realise what was happening in the cockpit.
"It's not a normal thing to do and obviously they had a bit of tension building up there."
It was alarming, he said.
"I would say there was a lot behind the scenes that ... I don't know about."
Another passenger Melissa Gough said she was so shocked when she saw how the pilots had acted on the flight, it put her off flying.
"It made me feel really uneasy," she said.
"I'm not planning my next trip anytime soon."
Pilots needed to put any differences aside when they were responsible for so many people, Ms Gough said.
After the incident the captain was stood down for two weeks and the first officer for a week, and given counselling and additional training.
Air New Zealand's operational integrity and safety manager Errol Burtenshaw earlier said the captain did not respond or open the door because he was approaching a navigational waypoint, and in his cockpit monitor saw a cabin crew member rather than the first officer ringing.
Mr Burtenshaw said both pilots had learned a valuable lesson around the need to communicate better with peers.
The airline provided a report on the incident to the Civil Aviation Authority. CAA spokesman Mike Richards said it was satisfied with Air NZ's actions.
Aviation commentator Peter Clark said the incident showed it was time all airlines put a third crew member in the cockpit. "After [the disappearance of Malaysia Airlines flight] MH370 there's definitely questions being asked about whether there should be more than two people on the flight deck."
The Malaysia Airlines Beijing-bound Boeing 777 and its 239 passengers and crew vanished after the plane left Kuala Lumpur on March 8. A Malaysian investigation last month identified the captain as the chief suspect, if human intervention was to blame.
However, Geoffrey Thomas, the editor of AirlineRatings.com, said having three crew members in planes' cockpits at all times would be a "gross over-reaction" to the incident.
"I certainly do not believe it's time to have three crew in a cockpit -- not any possibility whatsoever."
Three pilots would "dramatically increase the cost of air travel", Mr Thomas said. But there should never be a time where a pilot is left alone in the cockpit.
A simple solution would be to ensure the pilot was never alone in the cockpit by having a crew member take the place of either of the pilots, should they need to leave, he said.
"There are very, very few incidents involving pilots and we don't want to over-react."
Mr Thomas had spoken with Australian airline officials who believed the incident was nothing more sinister than a misunderstanding.