An employee was loading a pallet of empty shells in the back of a trailer while standing on a raised liftgate when his foot became stuck under the pallet jack. While attempting to remove his foot from under the jack, he lost his balance, pulled down on the pallet jack handle, and fell on the floor. He landed on his right hip and suffered a contusion. The jack handle was engaged when he fell, causing the jack to move backward off the liftgate and fall on his left foot. He suffered a 1-inch laceration on his left foot and bruise on his left knee.