Catastrophe at the Jolie-Pitt palace in Venice!

On Friday afternoon, Angelina Jolie and son Knox, 20 months, caught some fresh air on the balcony of their rented $6.8 million palazzo. Little Knox (twin brother to Vivienne) clutched a stuffed toy bunny for the outing.

Sadly, the celebrity tot's hold on the doll wasn't firm enough. The furry friend slipped from his hands -- falling off the balcony and, ultimately, into the waters of the Grand Canal below.

Jolie, 34, gasped, held her hand over her mouth and laughed. Later shots showed that Knox wasn't bothered by his bunny's watery end.

As the actress films The Tourist, mother and son have been staying in Italy's famous city with his dad Brad Pitt, 46, and five siblings: Vivienne plus Shiloh, 3, Zahara, 5, Pax, 6 and Maddox, 8. "Her life seems to be about these children," an insider says of Jolie.