They weren’t the only celebs in attendance.
Hudson’s brother and star of TV's Rules of Engagement, Oliver, demonstrated his gift for dressing up, as well. He had a present attached to his waist à la Justin Timberlake and Andy Samberg's Emmy-winning Saturday Night Live skit and song, "Dick in a Box."
Kate’s guy-pal, Dax Shepard, was some sort of “early-'80s person,” a fellow partygoer tells me. “It was hard to tell what he was, but he was wearing parachute pants." And no, fashion designer Marc Jacobs didn't come as a Smurf. He was just showing off his new buzzed 'n' blue coif.
David Spade, Lukas Haas and Kurt Russell chose not to dress up, but my source wasn't clear if Goldie Hawn was in costume...or just being her kooky self. “She could have been, or she could just could have been dressed like she always does," the source says. "Like, her lipstick was smeared, but was it part of a costume, or was she just kissing too many people hello?"
The party—held at Kate’s L.A. home—went on until at least 3 a.m. Most of the guests, I'm told, spent the night dancing outside to tunes from an iPod.