These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Rotwang's robot who only gets a couple minutes of screentimehas become the film's unofficial symbol in pop culture. It's the only character shown on the film's most famous poster. Osamu Tezuka's version was inspired by nothing other than that famous image. Of course, technically, the Maria Machine actually has a ton of screentime, just not in that form.
In the new restoration, the thin man.
Faux Symbolism: (For Osamu Tezuka's Metropolis.) There's a nice bit where Tima is standing on the roof in a beam of sunlight, presumably recharging. A bird lands on her shoulder. They cut to another viewpoint, and she looks exactly like an angel.
The whole 1920s film.
Rule of Symbolism, for the most part. You have crucifixion imagery, giant clock face, personified Whore of Babylon, retelling of the Tower of Babel story, animated gargoyles personifying Death and the Seven Deadly Sins, a hidden church in catacombs, an inverted pentagram, talk about "brothers and sisters", the machine as Moloch...
Ho Yay: Freder is a very physical person◊. Especially with Josaphat and 11811. On the other hand, it's very firmly established that he loves Maria...
Macekre: If you compare the 1928 American release to the original film — editing by chainsaw, and Channing Pollock boasting about having rewritten the whole thing.
Misaimed Fandom: Partly. Adolf Hitler said Metropolis was one of his favorite films. The writer, Thea von Harbou, was a dedicated Nazi. The director, her husband Fritz Lang, divorced her and moved to Hollywood soon after the Nazi rise to power. The movie certainly doesn't have anything supporting the Nazi ideology, unless you take extreme liberties at interpreting the Aesop. It's directed against all forms of tyranny, from ruthless capitalism to mob rule.
Narm/Anvilicious: The ending. Even Fritz Lang admitted he didn't like it in an interview he gave several decades later. In an essay that is available in the booklet of the Masters of Cinema DVD, Jonathan Rosenbaum has this to say: "one of the lamest endings of any great film I can think of".
Nightmare Fuel: Evil!Maria is a sterling example of this. Her movements, her expressions, everything about her scream so horribly that this is something that looks human but isn't.
Uncanny Valley: An invoked example will the robot Maria, who despite looking human moves in a twitchy, insect like way and has odd facial expressions, to convey how different she is from a person.
Unfortunate Implications: According to Siegfried Kracauer, author of From Caligari to Hitler, the ending of the film, with the reconciliation of the Hand (Labour) and the Head (Capital) by the Heart (the Hero and the Heroine) infused real-world problems with sentimental concepts and metaphors of the sort that appealed to the Nazis, since it stated that class tension can be solved not by unionization or revolution but sentimental appeals of benevolence via quasi-Messianiac and religious "mediators". Josef Goebells in an article on the release cited those same metaphors for his liking of the film. So as such, the Nazis From a Certain Point of View, did find much in the film to serve their ideas, a fact which made Fritz Lang feel resentful of the film, he always stated that the ending of the film was a mistake and that it was only in place because he couldn't think of a way to resolve the film.
Vindicated by History: When it was first released it was a huge flop that nearly bankrupted Ufa, the studio that produced it. Now, it's considered the forerunner to all science fiction films ever. Including (and especially) Star Wars.