More famously this one gets credit for predating Inspector Gadget, whether or not it was the actual source of inspiration. Gadget was daft but coasted on technology, often disastrous, stupid luck, and borrowed genius from his friends. Here we have another such private dick wired with all sorts of gizmo that save the day, but is seen more shrewdly within the original context of inspiration: Sherlock Holmes, where all the machinations were cranked out in the mind.
Pulp lore tells us Nick Carter actually debuted a year before Sherlock Holmes so could not have been influenced, but historical adherence is hardly the point here. Nick Carter is as much the object of sheer movie enjoyment, as a kind of James Bond test run, as a hodge podge of the suave American movie icon, the private dick, the action star, the movie hunk, as of biting scrutiny. This is never more obvious than in his overt reliance to eccentric gadgetry to see him through. It's his fat, bumpy, Czech colleague, his Dr. Watson as it were, who finally brings Moriarty down, by sheer street-wise craftsmanship and a good mark.
It helps to know as background on what this is, that this is by the same filmmaker behind the anti-capitalist western farce Lemonade Joe.
Otherwise, it's as you know Czech comedy; a broadly surreal imagination centered nowhere, with no deeper, cultural identity other than visual, worked out in terms of representational theater or ballroom jazz. Lovely energy, but loud structure. Flowery visual gaudiness.
Example of this here is the business with mirrored selves. The bookish maid turns out to be the sultry cabaret dancer, seducing behind a cat mask. Our mysterious evil nemesis is the world's biggest crook. Nick Carter dresses up his Dr. Watson as himself, and appears a third time in the end as the dreamy lover.
What a more erudite filmmaker could do, say, is that he could center each of these shifting selves within a shifting part of the world, so that each new swirl with each new guise revealed a part that we didn't know before. This is merely a papier-mache costume party, kind of fun on the spot, but you had to be there.