Brownlee said not only rejected repaying the money, but even suggested that a minister should have accompanied them on the trip.
"There was also an announcement made there by the ambassador about the enhanced partnership between New Zealand and Japan, which has been announced by the Foreign [Affairs] Minister.
"Very surprising to me that there was actually no minister there to do that."
He said the programme, facilitated by the Ministry of Foreign Affairs and Trade, was about building good relationships with the Japanese Government just before the CPTPP trade deal kicks in at the end of the year.
"We've just spent probably many tens on millions getting a CPTPP that will give NZ enormous opportunities to trade to all 11 countries ... Japan, an old market for us, will see the reduction of beef tariffs and other such.
"In the end it's the people to people things that matter most, like most things in life."
He was supported by Bridges, who noted that Japan was about to host the Rugby World Cup and the Olympics, and Ardern, who also pointed to the importance of the CPTPP.
Ardern said she had no issue with Mallard and Brownlee going to an All Blacks game as long as the trip promoted New Zealand's interests.
"My expectation would always be that the primary purpose is deriving greater, wider support for New Zealand's proposition abroad. My understanding from what I've seen of the programme is that it aimed to that as well."
She said a Trade Minister would normally promote trade with Japan, but it's not unusual for senior MPs to do so as well.
"We of course are not able to travel consistently. Making use of other members who hold relatively significant positions is something that we do. The Governor-General travels on behalf of New Zealand from time to time and we get benefit from that as well."
Former Speaker and National MP David Carter said he would not have gone.
"The public will make their own judgment. I would not have done it."
In a statement today, the Speaker's office said Mallard and Brownlee met with around 200 business and political leaders as well as officials involved in RWC2019.
"These included the Japanese Speaker, former New Zealand PM Scholars, key contacts with NZ businesses in Japan, senior politicians, and members of the NZ Parliamentarian Friendship League.
"The main feature of the trip was a reception at the embassy to which NZ exporters invited their Japanese contacts."
Prior to leaving, Mallard said in a statement: "Rugby and sport loom large in New Zealand's international identity and I look forward to the excellent opportunity this provides to promote New Zealand's collective interests and build valuable people-to-people connections."
The $24,000 is part of the Inter-Parliamentary Relations (Office of the Clerk) budget, and was intended to be used, in part, to promote New Zealand.