YMMV / Arsenic and Old Lace

• Big-Lipped Alligator Moment: The film opens with a fight breaking out during a Brooklyn Dodgers baseball game at Ebbets Field. The movie will never return to that, outside of a bare mention of the team winning the Pennant.
• Harsher in Hindsight: At one point Mortimer mentions that one of his ancestors had "scalped the Indians", as proof of how crazy he was. As a matter of historical fact, white people did scalp Native Americans throughout the various conflicts between them. However, since most white Americans didn't know these facts when the play and movie were written, it doesn't break the Suspension of Disbelief for the audience when Mortimer tells this story to Elaine.
• Hilarious in Hindsight: The aforementioned baseball game is played on Halloween, something which would have been ludicrous in 1944,^note The two latest endings to the World Series at that time were October 23, 1910, and October 26, 1911; excluding that two-year span, no major league game had ever been played later than October 16 but has happened several times since the Turn of the Millennium due to Major League Baseball's ever-expanding postseason.
• Memetic Mutation: Jonathan's most elaborate torture method ("Not the Melbourne method!") has attained a small fame of its own. As of 2010, it is the name of an album by the Mabuses and a business – the latter is even located in Melbourne, Australia.
• Nightmare Fuel:
  • Jonathan. The fact that he's in a film where everyone else is just charmingly kooky makes for quite a contrast. His fond reminiscing about the "Melbourne Method" utterly horrifies Dr. Einstein, and it's heavily implied that this flat-out torture which lasted two hours was inspired by Jonathan's decades-long desire to kill Mortimer, whom he also tortured when they were children — "Remember the time you were tied to the bedpost- the needles under your fingernails?"
  • The Brewster aunts are a perfect example of the fact that, when it comes to serial killers, They Look Like Everyone Else. It doesn't matter how nice they are, the reality still stands that as the story begins they have eleven dead people buried in their basement and have just poisoned a twelfth victim, and they never think that they did anything wrong.
• Special Effect Failure: In the "outdoor" scenes, the obvious soundstage backdrop of the Brooklyn Bridge and Manhattan is jarring to modern audiences.
• Values Dissonance:
  • The paternalistic tone Mortimer constantly takes towards the elderly women who raised him doesn't always sit well with modern audiences. It's notable that he grows more paternalistic as the story progresses, he realises just how insane his aunts truly are and becomes increasingly frustrated with their failure to understand that poisoning people is "not just against the law, it's wrong!!!"
  • The treatment of mental illness hasn't exactly aged well. Not only is mental illness mocked and Teddy unwittingly made an accessory to concealing multiple murders, but there is a strong implication that the mentally ill should be segregated from the rest of society. No one finds it at all surprising that the police want to involuntarily commit Teddy for a series of noise violations (sadly, was Truth in Television at the time).
• Values Resonance: ...or has it? The obviously mentally ill character, Teddy, is harmless, and loved by everyone (save for the people making the noise complaints!) to the point that even the villain's henchmen puts his foot down when the idea of harming Teddy comes up; meanwhile, the homicidally insane characters are the seemingly sane, well-liked aunts. The idea of sending Teddy to Happy Dale isn't much different than what elderly parents often plan for their mentally disabled children, and the asylum is implied to be a pleasant place, not the den of deadly lunatics that many other films in that era portrayed asylums as. Not only that, everyone works with Teddy. They dismiss convincing him that he's not actually Theodore Roosevelt because it upsets him so much and they find an in-character reason for him to go to Happy Dale to make it easier for him, rather than packing him off in a straightjacket. They don't try to forcibly cure him, they help him find a way to live once his aunts are gone.

---