Sexism
I know this film was made in 1952 and the Mitchum's character was a manly man but wow, the sexism here stood out for me in this film more so that any other that I can remember.
Like when Frank first meets Diane. He creeps up on her playing the piano and when she gets upset and bursts into tears, he (a man she had never seen before) grabs her up and instead of comforting her, basically tells her to get over herself and then smacks her when she doesn't calm down. I guess it was ok for a man to put his hands on a strange woman and rough her up some back in the day.
Later, after Diane follows him to the diner and they decide to go out to eat, he walks out and sees her snazzy sports car and immediately jumps in the driver's seat without asking, because no way is a mere woman going to drive when he's around (that bit of sexism would have served him well at the end though).
I love movies from the 30s and 40s and I'm sure their are blantant expamples of sexism in nearly all the good classics but for some reason this films sexism was extremely distacting for me.