Things with things sticking out the sides can fly. This includes the Polly Pocket car when it's doors are open. When it lands, the wings must be closed so it can drive. Things in the air have different sound effects than things on the ground.
Things with no wings can fly if two of them are stuck together. Two matchbox cars can fly. Two books. Two fingers.
Nothing can fly unless it starts out between your feet while you crouch down and say, "Three! Two! One! Blast off!" Having a second person saying the words with you is required in nearly all situations.
Charlie's favorite rocket is formed by pinching his thumb and index finger tightly together while the other fingers curl into a fist. I have seen him entertain himself for as long as forty-five minutes by making his finger rocket fly. One day, he approached Daddy, broken-hearted. He held out his hand, making the sign language letter L, demanding, "Fix it!" It took Dowlan a bit before he realized that Charlie was asking for a rocket repair. He pushed the thumb and index finger back together and the rocket was again ready for launch.