NEW YORK − New York Film Festival gave Jesse Eisenberg the perfect birthday present: A splashy premiere for his new movie.

"A Real Pain," the latest film directed by the "Social Network" actor, screened Saturday, which happened to be his 41st birthday. At the end of a post-screening Q&A, star Kieran Culkin and producer Emma Stone pointed their microphones at the crowd so they could shout "Happy Birthday" in unison to Eisenberg, who joined virtually wearing what he described as his "birthday tux."

There was, though, no singing, and Eisenberg seemed relieved. "My wish has come true," he joked.

In addition to directing and writing, Eisenberg also stars in "A Real Pain" opposite Culkin. But during the playful Q&A, Eisenberg admitted he "wasn't exactly very familiar" with the Emmy-winning "Succession" star's work before casting him.

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"Completely unfamiliar," Culkin quipped. "And you act like this is a normal thing to cast somebody without an audition and not having seen their work." Later, when the conversation had seemingly moved on, Culkin brought this up again and joked, "I had no idea he didn't know my work."

After Eisenberg explained that he was drawn to the actor's "unusual essence," Culkin playfully shot back, "You met me, like, twice − in passing! And you were like, 'Take this job.' Weird!"

But for Eisenberg, Culkin was the perfect person to capture the movie's complicated mix of comedy and heartbreak. "Is there a better performer on the planet who could do this kind of thing with such magnetism and pathos?" he asked.

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Eisenberg and Culkin star in "A Real Pain" as David and Benji, a pair of Jewish cousins who take a tour through Poland while visiting the childhood home of their grandmother, who has recently died. The film strikes a tricky tonal balance, combining a "Planes, Trains and Automobiles"-style road trip comedy with a somber reflection on the horrors of the Holocaust.

One of the movie's most harrowing scenes sees the characters visit a concentration camp, which had a profound effect on the actors. Jennifer Grey, who plays another member of the tour group, recalled feeling nauseated during the scene and becoming so upset that Culkin "swaddled" her after it was over. "There are no words for what I felt in my body," she said. "I can only assume it was some kind of generational grief."

The story was personal for Eisenberg, who has family roots in Poland. He previously took the same tour featured in "A Real Pain" and even filmed part of the movie at the actual house where his aunt grew up.

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By producing "A Real Pain," Stone extended her working relationship with Eisenberg, with whom she co-starred in 2009's "Zombieland." Before the screening, the Oscar winner remembered she "fell in love" with Eisenberg first as an actor and then as a writer. "I've known Jesse for a really long time," Stone said during the Q&A, adding that it has been "incredible to see him blossom into this truly wonderful director."

But the standout of "A Real Pain" is easily Culkin, who got big laughs throughout the screening, and he often manages to land a punchline and break the audience's heart within the same scene.

Culkin seems likely to contend for a best supporting actor Oscar nomination. As he explained to the crowd, though, he attempted to back out of the project multiple times, only to learn the film might fall apart if he did. "When (Eisenberg) asked me to do it, it was like a year out," Culkin said. " 'Yeah, yeah. That's next year. Fine. I'm going to be dead. It's fine. Let's do it.' And then it became real."

David and Benji's personalities are quite different in the film in a way that's played for laughs, with the former being socially anxious and the latter personable but blunt. In real life, both actors agreed they're also quite dissimilar − though Culkin noted that "for some reason," this was a surprise to his co-star.

"You came to my trailer once and you were like, 'Did you think that you and I were going to be alike?' " Culkin said, addressing Eisenberg. "And I was like, 'No. Why, did you?' And you went, 'I did.' And then you walked away, scratching your head."

Summing up the difference between them, Eisenberg quipped, "Kieran lives in what he told me was called 'the moment.' So that was interesting for me to hear about."

"A Real Pain" is set to arrive in theaters on Nov. 1.