The trip happened just before the show first aired in 1994 and before the cast – Cox, Jennifer Aniston, Lisa Kudrow, David Schwimmer, Matthew Perry and Matt LeBlanc – became some of the most famous actors in the world.
“[Jim] gave us all $500 (£380),” Cox told Today’s Willie Geist. “And he said, ‘I want you to take care, like, really take notice of this moment because it will be the last time that all six of you together can walk through a casino.’
“And we were like, ‘Really?’ And it was true. We could never do that [again].”
She added: “I mean, I don’t wanna sound like, ‘Look at us.’ We’re not, you know, the Beatles. But people feel like they know you.
“If we were all to walk down the street, six of us, it would be, I think it would be really interesting to people.”
In the same interview, Cox admitted that she “doesn’t remember filming” so many Friends episodes.
Cox can currently be seen in the horror comedy Shining Vale, out on Starz.
Read our ranking of who’s had the best career since Friends, here.