There had been much made of the fact that athletes from South Korea and North Korea, long enemies in a cold (and sometimes hot) war, entered the arena together to signify in the importance of setting aside political issues in order to highlight the athletic and competitive integrity of the Olympics.
Images from the lunch meeting at the Blue House, which was broadcast live on South Korean TV, showed Moon sat in front of Kim Yo Jong, rather than Kim Yong Nam, technically the more senior official present in the meeting, and head of the North Korean delegation.
The South Korean President has been invited to travel to North Korea, following a formal invitation from the country's leader, Kim Jong Un, potentially setting up the first meeting of Korean leaders since 2007.
A top North Korean official seemed to rule out a potential meeting with USA officials in the North's state-run media on Thursday, but Pence suggested to reporters that it was still a possibility.
But he pointed out that whenever the North's state media reel off the names of officials who attend ceremonies, "Kim Yong Nam's name always comes next after that of Kim Jong Un".
But away from the spotlight, these two unwanted guests, men dressed as North Korea supreme leader and the U.S. president, were escorted away from the premises.
There was USA vice president Mike Pence's warning that even though he was attending the opening ceremony, he wasn't going to enjoy himself (or something like that).
NASA probe "New Horizons" snaps farthest-ever photo from Earth
Well, New Horizons has outdone itself again, setting a record for the farthest photos ever taken from Earth. The targeted object is known as 2014 MU69; the spacecraft will pass within 2,175 miles (3,500 kilometers).
"The North Koreans should understand that for a summit or any kind of serious talks to occur, Moon needs to be able to take something to Washington - something that addresses denuclearisation", he said. "That is a very odd time, if in fact he is trying to show a warming", Mattis said, referring to Kim Jong Un.
On Saturday, he tweeted that the U.S. would not "allow the propaganda charade by the North Korean regime to go unchallenged on the world stage".
Kim, president of the Presidium of the Supreme People's Assembly, is leading North Korea's delegation to the Olympics.
Some North Korean experts believe tough United Nations sanctions that are cutting off most of the isolated regime's sources of revenue might pressure Pyongyang to further engage with Seoul.
Five gold medals are up for grabs on the first day of full competition in the Winter Olympics on Saturday, which features the debut of a unified Korean ice hockey team.
Abe is expected to urge Moon to steadily implement the deal, arguing that Japan has been carrying out its promises, Japanese government officials said.
Mr Pence said the U.S. would "demand at the outset of any new dialogue or negotiations that the Kim regime put denuclearisation on the table and take concrete steps with the world community to dismantle, permanently and irreversibly, their nuclear and ballistic missile programmes".