80s stuff. Mostly because as an adult, I'm aware at how unrealistic most of the stuff is in their action and comedy films. Most comedies would end halfway through as the cast was arrested for the various felonious hijinks they caused during that "fix-em-up" montage, and most action movies would end in the first act as the hero didn't survive that grenade blast or gunshot to the shoulder.
I'll tell ya a weird one: MacGyver episodes. When I was a kid, MacGyver was THE SHIT because he could invent anything on the spot. Watching episodes as an adult, I realize that "Hey, isn't it convenient that everything he needs is in the very room he's usually trapped in?" There's never a missing piece. He never gets 7/8 pieces together and then the 8th piece is missing and he can't go through with it.
But the best example I can think of is not so much a film as much a scene:
Back to the Future.
I love BTTF, as much as an adult as a kid, although in different ways. But there's one thing that is fundamentally different for me now that was definitely not there in the 80s and 90s.
At the scene at the 1955 clock tower as the storm is building up, Doc finishes briefing Marty on the whole lightning-bolt setup he has ready to go and gets out of the DeLorean and says "Well, I guess that's everything!" and Marty realizes that he has to go. Up until this point, Doc has refused to let Marty tell him about the future, completely unaware that Marty is trying to save his life in the process, and Marty has been polite about it. But now, Marty's time is up and he has to leave Doc behind, and return to the future, never to see him again. Realizing that he is about to lose his best friend in the world for the
second time, and being powerless to do anything about it, Marty grabs Doc in an embrace--gripping him as hard as he can and holding back tears; the desperate, clinging urgency of someone who is saying "goodbye" for the final time and knows it. Doc, confused by the passion in Marty's gesture, casually says "In about 30 years?" and Marty responds "I hope so" choking on every false word as it comes out.
It's a small moment, less than 10 seconds long, and it's absolutely devastating.
When I was a kid in the 80s and 90s, it was just a moment that was part of the dramatic logic of the scene. It made sense to me, but it didn't affect me; the scene of Doc getting shot by the Libyans was more traumatic. But in those days, I hadn't lost anyone close to me. In the years after, I lost a number of people I cared the world about, and I felt that their passing took the reasons for living with them. Now that moment when Marty grabs Doc as if he was a piece of driftwood in a hurricane feels like a spear in the gut. To have the chance to see again someone you lost is already moving and powerful enough, but to have to lose them again? Almost inconceivably painful.
And yet, Marty McFly manages to convey all the gravity of unspeakable longing, regret, love, and anguish in a simple gesture that manifests what we all would feel if we were in his position: grab the one you love with both hands and never let go.
That's the one thing that watching a lot of childhood movies as an adult does to you: it makes the pain and loss all the more potent.
Especially nice is the scene where a bear licks honey off of the bare soles of Joanna Barnes. 
