Ernie Stewart / Retna Digital 1 / 2
Ernie Stewart / Retna Digital 1 / 2

Brad Pitt and Angelina Jolie had an unexpected guest at their private dinner in Cannes, France, Tuesday night.

Twilight star Robert Pattinson arrived at the Michaelangelo restaurant in Antibes just as the star couple were saying their goodbyes at the Inglourious Basterds fete.

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"He arrived as Brad and Angelina were leaving," a restaurant source tells Usmagazine.com. "But they spoke in the hallway. It didn't seem like they knew each other that well, but the conversation was friendly. Brad shouted back to Rob, 'Go inside and get something to eat.' They all seemed happy."

Pitt and Jolie dined with the cast and crew of his new film the night before the Cannes Film Festival premiere of Basterds. The two stars left their hotel, Hotel du Cap, and arrived at the restaurant at 11 p.m., along with director Quentin Tarantino, Harvey Weinstein and costar Diane Kruger -- who was joined by boyfriend Joshua Jackson.

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"It was really lively and friendly," the source tells Us, adding that the group dined on focaccia bread, prosciutto, truffle ravioli and rigatonni with sausage. "Everybody was relaxed and being themselves. Quentin Tarantino was the center of attention, telling stories and making everyone laugh."

When Pattinson -- who walked the red carpet at Wednesday's premiere of Basterds -- arrived at the restaurant, the chefs rushed to serve food to him and his group of four people, including Emile Hirsch and Brianna Domont.

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"There wasn't much left, but they were all given something to eat," the source tells Us. "Just simple food."

Before leaving, the actor -- who just celebrated his 23rd birthday this week -- took photos with the restaurant's owner, Mamo.

"He was nice," adds the source. "Very friendly."