Jessica Alba's daughter thought mom dressed as cartoon alien for film

Actress JESSICA ALBA was left horrified after taking her daughter Honor to watch her first kids' movie ESCAPE FROM PLANET EARTH because the four year old couldn't tell the difference between live action and animation.

The Sin City star voices villain Lena Thackleman, a scheming big-headed blue alien, in the animated adventure and she was excited to show her eldest child the finished product.

She tells the New York Daily News, "Rarely do I get an opportunity to make a move that my kids can see. When it comes to me doing movies, she'll come on the set and pretty much think I sit in a trailer and get different hair and make-up done. She has no idea. So it's nice to show her this is what I do."

However, Alba didn't quite expect the reaction she received: "She did ask me, though, after she saw it, 'Mummy, was it hot when you wore that mask?' Was it hot? I was like, 'Oh, my God, she doesn't know the difference between live action and animation!'"

Alba isn't the only celebrity in the movie - Brendan Fraser, Ricky Gervais, Sofia Vergara, Sarah Jessica Parker and Jane Lynch also lend their vocal talents to characters in the film.