The Phantom Empire: Chapter 04 - Phantom Broadcast (1935)

Synopsis
Seconds before his automobile crashes over a cliff, Gene Autry is saved by Frankie (Frankie Darro), Betsy (Betsy Ross King) and the Junior Thunder Riders. Still wanted for the murder of his Radio Ranch partner, Gene is forced to broadcast from Frankie's secret laboratory in the barn. Meanwhile, down below in Murania Queen Tika (Dorothy Christy) is troubled by the rebellious Lord Argo (Wheeler Oakman), who is eager to blow up Radio Ranch once and for all. Finishing his broadcast with a rendition of "Uncle Henry", Gene manages to escape before Professor Beetson (J. Frank Glendon) and his men break down the door to the laboratory but spilled gunpowder creates an explosion in the getaway tunnel. ~ Hans J. Wollstein, All Movie Guide