The device that Prof. Erasmus (Rudolf Fernau) wears on his chest is the same prop that was used in The 1,000 Eyes of Dr. Mabuse (1960) as a remote control for the blast door in the basement of the Hotel Luxor.
Since many Americans were not familiar with the name "Dr. Mabuse," this film was also distributed in the US in its dubbed version as "The Invisible Horror."