photo courtesy

We're on the set of the Anna Faris comedy 'House Bunny' with Rumer Willis and Katharine McPhee!

Why is RUMER WILLIS wearing a back brace, and what's up with KATHARINE McPHEE's baby bump?

Did the progeny of BRUCE WILLIS and DEMI MOORE have an accident? No, Rumer's just wearing a prop for her new film, 'House Bunny,' which stars ANNA FARIS!

The movie prop has proved a little cumbersome for Rumer on the set. "I keep bumping into people and having to apologize to everyone," she says. "It's fun though."

And while "American Idol" runner-up Katharine tells "The Insider" she does want to have kids someday, the round belly she's sporting is actually just a prop for the film!

"The prosthetic belly [wraps] all the way around [to] my back, and it's actually really comfortable," says Kat. "I'm really enjoying it. [But] I think it'll probably hold me off a bit on having a baby."

"It's fun to just pretend and look in the mirror," adds Kat.

"The Insider" is on the set of the new comedy, which centers around a Playboy bunny named Shelly (Faris) who gets kicked out the mansion and finds refuge with a group of geeky sorority sisters from Zeta Tau Zeta. The seven sisters are about to lose their house until Shelly rescues them with her sparkling personality and teaches them how to be themselves.

COLIN HANKS co-stars in the film, which will hit theaters in 2008.