"I think the first time we really started hanging out is when we shot No Strings together," Kutcher said, to which Portman responded: "Who would've thought 20 years later, we'd be on a Peloton together?"
Kutcher then said: "Wait, it's also weird because my wife was shooting basically the same movie, called 'Friends With Benefits'."
Both Ivan Reitman's 'No Strings Attached' and Will Gluck's 'Friends With Benefits' are about a man and a woman who decide to turn their friendship sexual without becoming a romantic couple, realising later that that's more complicated than they thought.
Both films were successful. No Strings Attached made a higher profit domestically $70 million versus $55 million, according to Box Office Mojo.
Curiously, both films earned almost the same amount worldwide, $149 million. Friends With Benefits had a slightly higher budget, $35 million versus $25 million for the other movie.
On Our Future Selves, Kutcher's interview and marathon training series with Peloton, Portman also raised another curious point to her former co-star.
"And Mila and I had just shot Black Swan together. So we were all making out with each other."
Darren Aronofsky's 'Black Swan', a 2010 ballet thriller, was more than twice as successful at the box office than the rom-coms, making more than $329 million worldwide.