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.
Adaptation Displacement: Like with many other Hitchcock movies, the book that it was based on is pretty much forgotten.
Harsher in Hindsight: The scenes of Grace Kelly's character driving recklessly can take on a different feel once one realizes that they were filmed in the same vicinity as the site of Grace's fatal 1982 car accident.
Like You Would Really Do It: Robie's the hero of a comedic romance film, he's not going to really let Danielle fall off a building, but SHE doesn't know that and makes a full confession.
In the original script, he was actually much more of an asshole about it and it went on longer, but it was felt that this would kill audience sympathy for him dead, so the scene was altered to be shorter and Robie is more crazy-desperate than needlessly cruel.