Kate Hudson's 5-year-old son has a crush on Penelope Cruz.

While Hudson and Cruz were shooting "Nine" (out Dec. 25) together, Ryder would point out Cruz, saying, "I saw Penelope in the lobby today," Hudson tells "Extra."

Says Hudson, "You could see that he recognized what a beautiful woman she is. He's so cute!"

Hudson was in awe of co-star Sophia Loren.

"She's just incredibly elegant and beautiful," Hudson says. "And the work she's done, and the people she's worked with. It's like a living legend, an icon!"

Hudson says she became close to Cruz, Fergie, Nicole Kidman and the rest of her "Nine" co-stars because director Rob Marshall set up a green room where they all hung out.

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"It's a great way to work. You create great friendships and intimacy," she says.

Their favorite topic of conversation?

"If you're a mom, you're always talking about your kids," she says.

See more of "Extra's" interview with Kate Hudson tonight!