"Dr. Cyclops" is a 1940 American science fiction horror film directed by Ernest B. Schoedsack, known for being the first horror film made in full three-strip Technicolor. It follows the story of Dr. Alexander Thorkel, a mad scientist who shrinks his colleagues to microscopic size in his jungle laboratory. When they threaten to expose his experiments, he uses his invention to miniaturize them. The scientists must navigate the dangers of the jungle while trying to escape Thorkel's clutches.
You can stream Dr. Cyclops (1940) (1940) free and legally on alltube, via the Internet Archive.
Yes — it is in the public domain and can be watched and shared freely.