As at many diplomatic gatherings, the real action at the annual Group of 7 summits often occurs on the sidelines, where world leaders mingle and make small talk that occasionally gets picked up by lurking microphones. These hot mics, as they are known, seemed to be working overtime on Tuesday, recording snippets of conversations that ranged from geopolitics and trade to the leaders’ personal lives.

“We are friends again,” said António Costa, the president of the European Council, as he stood, flanked by President Trump and Prime Minister Giorgia Meloni of Italy. Ms. Meloni had appeared to be distancing herself from Mr. Trump in recent months, after the outbreak of the U.S.-Israeli war in Iran, which is deeply unpopular in Italy.

“We have always been friends,” Ms. Meloni insisted, smiling at Mr. Trump, according to video footage that also captured the moment.

Mr. Costa was involved in another fascinating, if inconclusive, exchange with Mr. Trump. Huddling before the start of a session, Mr. Trump turned to him and said, “You understand,” then added, “Greenland.”

No other part of the conversation was picked up by microphones, leaving observers to let their imaginations run wild about Mr. Trump’s previous threats to take over Greenland, which has been perhaps the most divisive single issue between the United States and its European allies.

Another exchange, between Mr. Trump and Prime Minister Mark Carney of Canada, was more revealing. Chatting about a deal made between Canada and China on the imports of Chinese electric vehicles earlier this year — a deal that the Trump administration did not like — Mr. Carney could be heard telling the president that it covers “less than three percent of our market, 49,000 cars.”

“I thought you’d actually like that,” Mr. Carney said.

“That’s good,” Mr. Trump replied. “I like that.”

President Emmanuel Macron of France, the host, gave his guests an excuse for mild high jinks after he appeared to have left his wristwatch behind after lunch.

“He’s left his watch here,” Mr. Carney said to the group. “We’ve got his watch.”

“Give me it if he left,” Mr. Trump said as others nearby laughed. “Gimme.”

The personal habits of Italy’s prime minister also provided a feel-good moment as the leaders milled around before their first meeting. When Chancellor Friedrich Merz of Germany asked Ms. Meloni if she had smoked her first cigarette of the day, she replied that she had not smoked “since the first of May.” Bathing in praise from the group, she threw up her arms in mock victory.

“Do you have a patch?” Mr. Carney asked, grabbing his own arm.