• Alternative Character Interpretation:
    • Is Hans really unable to control his impulses? How strong are they? Do they even exist or is the whole insanity thing a sympathy play to justify his crimes?
    • Even the mob aren't beyond this. Are they really solely concerned with their own well being and not with justice? If so why not just shoot Hans and be done with it? Why hold a trial where his evils are spelled out, why provide a defense advocate to argue for him?
  • Ensemble Darkhorse: Otto Wernicke's Kommissar Lohmann was so popular with viewers that Lang brought him back for Das Testament des Doktor Mabuse one year later.
  • Fridge Horror: Complete with Inferred Holocaust, considering what mental hospitals were like in the 1930s, the death penalty might be kinder for poor Hans; he's pretty screwed either way.
  • Harsher in Hindsight: Or at least, ironic in hindsight. Der Schranker, the faux-Nazi head of Berlin's underworld, is played by Gustaf Grundgens, who became director of the Prussian National Theater under the Nazis and a favorite of Hermann Goering.
  • Jerkass Has a Point: The prosecutor of the mob trial may be a criminal but he does have a point that whether or not Hans is crazy he is a threat to the children of Germany regardless and killing him would make them more safe.
  • Misaimed Fandom: The Nazis. They even took Hans speech at the end to "prove" that Jews were all evil. Because Peter Lorre was Jewish, and he played a Serial Killer, that means that all Jews are serial killers, right? It's doubly ironic from the lawyer's equally-impassioned speech in which he states, "No one has the right to kill a man who is incapable of responsibility for his actions! Not even the state!"
  • Moral Event Horizon: Subverted for some, in that you'd expect the act of murdering little girls to automatically lose the audience's sympathy and yet many feel bad for him. It is arguably a great example of someone who does monstrous, unforgivable things and can still retain deep down some sympathy. That's why there are those who see him as a...
  • The Woobie: Only Peter Lorre could make a child killer into one.
  • Woobie, Destroyer of Worlds: Arguably the Trope Codifier.