The actress was presenting a prize at the ceremony in Burbank, California when footage of her as a youngster, dancing and singing about the benefits of recycling, began to roll.
Portman laughed off the embarrassing gag and went on to hand the EMA Corporate Responsibility Award to Jeff Skoll, producer of The Cove and environmental movie The Crazies.
Veteran Hollywood star Jane Fonda also showed up to honour her ex-husband Ted Turner for his foundation’s work in stopping female genital mutilation, reports EOnline.com.
The ceremony, which pays tribute to TV and films with a positive environmental message, also saw James Cameron’s Avatar win the top movie prize.
Hit sitcom 30 Rock and TV drama Bones were both honoured for episodes which tackled conservation themes, while HBO documentary Gasland, about natural gas drilling in the U.S., was also celebrated.
