Just about every sci-fi film made from the 1930s onward references this movie.
Yep, there is a book. It was written by Thea von Harbou, the screenwriter and Lang's wife at the time.
Alternative Character Interpretation: The multiple, different cuts of the film in particular have made a lot of the characters open to interpretation.
Does Freder find religion due to Maria's influence (as the novel makes clear), or was he already a believer? Is he a Neutral No Longer former enabler who only takes a stance against the city's injustices when confronted by them, or a generally good person who didn't even know about said injustices beforehand? Does he fall in Love at First Sight with Maria because of her actions, or does he at least initially do everything for her mostly because he thinks she's hot? Also, his Hot-Blooded nature and his visions could simply be seen as a side effect of living in a World of Ham and Symbolism in the film, but the novel has him actually question his own sanity after a while.
In Harbou's novel/screenplay, Joh Fredersen wants the robot to start a form of False Flag Operation, and orders Grot to let her revolutionaries into his machine room. Pollock changes this dynamic so that the robot carries out the uprising on her own accord, while Fredersen orders Grot to stop the revolutionaries from reaching his machine. Unlike the book, the film also doesn't focus much on Joh Fredersen's Character Development, making it less clear if he's had a change of heart as intended, or is simply an evil man who cares about his son, and eventually shakes hands with Grot because he quite frankly doesn't have much of a choice by that point. In general, Fredersen seems not as tragic in the film as in the novel — and even less so in the Pollock cut — simply because the time spent with him being The Atoner has been reduced.
One of the main ones is if Evil Marie/Babylon is a sadistic and souless psychotic machine or a Tragic Monster wrought by the madness of Dr. Rotwang who never really had a choice to be anything but what she is, or maybe some combination of both. Her Pollock incarnation is explicitly the former, with Fredersen playing no part in her revolution. The Lang cut makes her more like an enslaved Psycho for Hire, gladly carrying out her master's orders. The book raises more questions by having Rotwang chide her for being "too violent" after nearly tripping onto Joh. Is he just joking about what was clearly an accident, or was she subtly trying to attack him in a way she could get away with? And what to make of Rotwang's claim from the same chapter that she can "play the affectionate" or "the sulky?" Can he reprogram her personality at will, or is she a malevolent being which could only ever pretend to be something else?
Rotwang changes completely from version to version. In the Pollock cut, Rotwang is Joh Fredersen's loyal servant who loses control of his creation after she becomes a Robotic Psychopath, and later tries to kill Maria to cover the whole thing up. The Moroder cut makes it clear that there was a lot of Teeth-Clenched Teamwork between Rotwang and Fredersen, as they were both involved with the same woman. The novel additionally portrays him as The Corrupter, but also gives him a Heel–Face Door-Slam where he almost ends up ruining Fredersen's revolution plan. In the Lang cut, he's seemingly behind said revolution plan as he orders the robot to destroy the city in a deleted scene. That's not even taking into account works like Metropolis the Musical, where he's a completely innocent Reluctant Mad Scientist, or Superman's Metropolis, where his counterpart is the Man Behind the Man, controlling the city master using mind control.
Is the Thin Man really as cruel as he first appears? Is the concern he shows Freder and Joh indicative that Even Evil Has Loved Ones, or that his Smug Snake persona is mostly an intimidation tactic? When he tells Joh that his plan might end up killing countless innocent children, is he just being Brutally Honest, or is he stoically giving his boss a "The Reason You Suck" Speech? In the book, does he try to shut down the Maohee den because it was illegal or because he saw the clear damage it could cause on its users.
The film plays Georgy as a pretty normal guy, whereas the book portrays him as a straight-up Mad Prophet.
Awesome Music: The original reconstructed soundtrack by Gottfried Huppertz, which answers a question very few people ever thought to ask: What if Richard Wagner wrote a film score?
"Cage of Freedom" from the Moroder version. Really, most of the Moroder version's soundtrack is pretty awesome, though YMMV whether it fits the movie or not.
Aluminum Christmas Trees: The Paternoster Lift — mentioned in the novel and shown off in a deleted scene — seemed so strange to some that it may be mistaken for another sci-fi movie prop. It was actually a real type of lift, still manifactured up until the 1970s. Some of them are still in operation to this day.
Better on DVD: Way better, especially now that the movie has been almost completely reassembled and released on DVD and Blu-Ray.
Opinions on the Moroder version are sharply divided, to say the least. Is it the way to watch the movie, due to its All-Star Cast of musicians? A good alternate take on a classic film, if not as great as the Truer to the Text versions? Decent, but only when it's a real silent film and not a damn music video? Or is it a Narmful mess with Gratuitous Special Effects comparable to the special editions of the originalStar Wars trilogy?
The False Maria's striptease. Is it genuinely erotic, too ridiculous to be taken seriously, a prime example of Nightmare Fuel, or a combination of all of the above?
Thea von Harbou's novel. Is it a good piece of supplementary material with better characterisation and more Worldbuilding than the film allowed for, with some interesting symbolism as well? Or is it just pretentious, overwritten trash which only became a watchable film thanks to Fritz Lang's directing skills and the lack of Narmy dialogue?
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.
Several viewers have felt that the scene where the False Maria dances around while wearing practically nothing is a lot less sexy than it should be due to Brigitte Helm's rather stiff and mechanical dance moves. They either turn the scene into Narm, or make it terrifying by plunging it deep down into Uncanny Valley territory. Though considering that she is an evil robot, the latter reaction might very well be exactly what Lang was going for.
Channing Pollock apparently thought the very concept of a Robotic Spouse was this, leading to him removing every mention of what The False Maria was built for. Unfortunately, this wasn't only a case of Adaptation Explanation Extrication, it also - along with the removal of the character Hel - led to both Rotwang and Joh Fredersen becoming less three-dimensional than they were originally.
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...
Jerkass Woobie: Joh Fredersen. On one hand, he is the creator and ruler of an oppressive dystopia and the initiator of a kidnapping and a False Flag Operation. However, it is also shown that he truly cares about his son and still mourns his dead wife. Alfred Abel's performance makes him come off as sympathetic and rather tragic as well as cold and ruthless. It's hard not to feel bad for him in the end, when he realises that Freder's life is in danger and has a complete breakdown.
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.
Memetic Mutation: VIP Teacher. Explanation In 2005, a scene from the movie was used in a video called VIP先生 paired with a cover version of "Rawest Forest" from Super Mario RPGWith Lyrics. It spread to 2channel and niconico, and the rest is history.
Misaimed Fandom: 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. To a normal person 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. However, in fascist and Nazi wishful thinking fascism and later Nazism had bridged the gap between worker and capitalist renouncing exploitation and decadence on one hand and mob rule and blind lust for destruction on the other. In their eyes this film is a tribute to or a prophecy of that great achievement. So the film falls heavily under this trope, as it portrays war, segregation, and facism as bad yet the Nazis were too self absorbed to glean the right message from the film.
Once Original, Now Common: A modern audience watching the movie would find it to be incredibly cliched and unoriginal. This, of course, is the movie that created most (if not all) of said cliches.
One-Scene Wonder: Moloch only appears once in a single vision in the movie, but man is it a memorable one.
Only the Creator Does It Right: The 2010 version, which is closest to Lang's original cut of the film, is generally considered to be the best version. The only real competitor is the Moroder version, which was made by people who were very famous and talented in their own right, and even that version is a case of divisiveness. However, this trope might be subverted in that the original novel the film was based on is also divisive, as many feel that the movie is actually better than the book.
Stock Footage Failure: The shot of Georgy first reading Josephat's adress card is clearly from later in the film, when he reads the same card in a taxi. (You can see his seated legs in the background, and the blinking lights which don't match the rest of the scene.) Incidentally, this makes it the one Yoshiwara shot to still exist in HD, as that whole subplot was cut by Pollock and only rediscovered later. (The 2010 restoration puts the card shot it the proper place and replaces it with a different one.)
They Changed It, Now It Sucks!: In hindsight, this is how many people view Channing Pollock's cut of the film. As each later version brought the film closer to its original state, it becomes a case of "they changed it back, now it doesn't suck anymore."
Unnecessary Makeover: Some viewers felt that The False Maria looked pretty attractive even when she was a robot. That said, the makeover is necessary In-Universe, since she has to look like Maria for Joh Fredersen's plan to work.
Vindicated by History: When it was first released it was a huge flop that nearly bankrupted Ufa, the studio that produced it. It was also trashed critically by Lang's former admirers and friends, who considered it the weakest of his silent epics, dismissed by H. G. Wells himself as "quite the silliest film". Now, it's considered the forerunner to all science fiction films ever, including but not limited to Star Wars, Blade Runner, The Terminator and A.I.: Artificial Intelligence.
Visual Effects of Awesome: Jesus wept, just look at some of the scenes in this film (like the vision of the Moloch Machine and the creation of the False Maria) and remember that it was made in 1927!
from the Moroder version. Really, most of the Moroder version's soundtrack is pretty awesome, though YMMV whether it fits the movie or not.