When Dr. Zorka drops the bomb on the dirigible, the stock footage is of the actual news footage of the explosion and crash of the Hindenburg.
CHAPTER TITLES: 1. The Menacing Power; 2. Death Stalks the Highways; 3. Crashing Towers; 4. Invisible Terror; 5. Thundering Rails; 6. The Iron Monster; 7. The Menacing Mist; 8. Trapped in the Flames; 9. Speeding Doom; 10. Phantom Footprints; 11. The Blast; 12. To Destroy the World.
The last of Bela Lugosi's five serials, shot April 24-early June 1939, after he returned from England, where he completed Occhi neri di Londra (1939).
The explosion and avalanche footage from Universal's The Vanishing Shadow (1934) is used in Chapter 11 of this serial as stock footage.
The scene in which Prof. Zorka is lowered into a pit while wearing a protective suit is taken from Il raggio invisibile (1936) and is actually Boris Karloff inside of the costume, not Bela Lugosi.