With a sub-barrel-bottomed budget, this Mexican horror outing features wicked old Dr. Krupp, a.k.a. "The Bat", the crazed experimenter who caused trouble in this film's two predecessors, The Aztec Mummy and Curse of the Aztec Mummy (both 1957), up to his old tricks. As in the former features, he is again trying to trick the Aztec mummy Popoca into leaving his crypt so the bad doctor can get at the treasure within. This time his scheme entails the invention of the title tin man (complete with incandescent light-bulb ears), a device he equips with a human brain. A horrific battle ensues when the two monsters collide.
Robot Monster provides examples of:
- Advertised Extra: The robot doesn't show up until the last ten minutes of the movie.
- Affably Evil: Dr. Krupp is nice enough to give Dr. Almada a belated congratulations for his wedding.
- Anti-Climax: The fight between the robot and the Aztec mummy only lasts about one and a half minutes.
- Artistic License History: The Aztecs did not, in fact, practice mummification.
- Cool vs. Awesome: Welllllll... it's what they were going for, anyway.
- Cyborg: Probably what they meant by "human robot". To be fair, this movie came out about 2 years before the term was invented.
- Dreaming of Times Gone By: Flora is hypnotized to remember her past life as the mummy's girlfriend, Xochi.
- Large Ham: Dr. Krupp.
- Mad Scientist: Doctor "The Bat" Krupp.
- Mr. Exposition: Dr. Almada. About two thirds of the movie is a flashback that he narrates.
- Mummy: One notably based on Egyptian mummies, despite being ostensibly Aztec.
- Tin-Can Robot: The "Human Robot" is a man wearing a number of tin boxes and a bucket over his head.
- Two-Faced: As shown by the extensive flashback footage, Krupp's henchman Bruno was burned by Popoca and holds a grudge towards it for having half of his face scarred.
- Versus Title: The title.