"I kind of laughed and thought, 'Well ... that's funny,"' Aniston told reporters recently, according to AP Radio.
She said working on the film during her own marriage breakup wasn't all bad. "I kind of found it -- something like a sign or something that, you know, to do it because it was sort of like in a way, umm, a cathartic thing."
Aniston divorced Brad Pitt in October, after 4 1/2 years of marriage.
The 37-year-old actress said she found her own experience beneficial to her role in the movie, which opened Friday.
"I felt very lucky in a way. ... If this had come to me at any other time in my life, I don't know if I would had been able to really get it -- for myself -- on the level that I would have wanted to as an actor."
Aniston reportedly has been dating her co-star Vince Vaughn. She described him as someone who is generous and thoughtful to work with.
"He asks questions, he listens, he's interested in other people, it's not just about him," she told reporters.
Angelina Jolie, Pitt's co-star in the 2005 film "Mr. & Mrs. Smith," gave birth to the couple's first child, a daughter named Shiloh Nouvel, in Namibia last week.
It was during the filming of "Mr. & Mrs. Smith" that reports of a romance between Pitt and Jolie began, which were later corroborated by photographs and public spottings.