A Wireless Lizzie(1929)

Walter has invented an automatic remote-control for his jalopy. When a potential buyer comes to look it over, Walter proudly shows how he cam the car stop and go, turn corners and steer correctly. His spiteful rival, Bill, switches the plug and the car runs out of control. Walter and his sweetheart, Mary, plan to elope but they discuss their plans in front of an open microphone at the broadcast station, and Mary's father hears it and sets out to stop their elopement.