The Volver actress was traveling on a Continental flight from Newark to Barcelona last Thursday, where she was headed to start shooting for Woody Allen latest film project.

Penelope was seating alone in first class as the plane began to taxi onto the runway when she became agitated.

After a short conversation with one of the flight attendants, the plane stopped and returned to the gate where handlers searched for Penelope's suitcase in the rain.

A passenger tells the paper, "She was freaking out and refused to fly."

Passengers on the flight eventually took off for Barcelona, TWO HOURS later.

Penelope's publicist told the paper, "There was no panic attack.

"The airline let her know there was going to be a three or four hour delay due to the storm. She had work so she figured she'd deplane and fly when the storm had passed."