Around 18 minutes 20 seconds into the movie Richard Pryor gets on a toy called the Wonder Wheel. We can clearly see that no one is near him. Around 18:39 we see a hand reach out and help push the Wonder Wheel. This must be some sort of stagehand. At the 18:48 mark Pryor crashes into some toys and starts moving the other direction (toward the right of the screen). At 18:54 the camera cuts to a closeup. At 18:56 we see the same hand reach up and push the Wonder Wheel to keep it going.