1. The Shining - "Here's Johnny!"
The Shining is a gripping, unique horror film that holds up extremely well and still looks incredible, but watching it now, one can't help but notice that the famous climactic "Here's Johnny!" line -- which is also the DVD cover -- ends up being a really minor part of the film's explosive final sequence. The Jack character painstakingly axes his way through the bathroom door while his wife screams, then he sticks his face through the door, delivers the line, and instantly gets stabbed in the hand then hears someone at the front door and leaves.
It's still a super-awesome and terrifying scene, it's just slightly amusing how instantly-defeated he gets. Then he gets outsmarted by his son and freezes to death. It's a pretty rough twenty minutes for that dude.
2. Say Anything - The Boombox Scene
I watched this film for the first time in college, having somehow missed it in my formative younger years, and spent the entire movie waiting for the famous Peter Gabriel "In Your Eyes" boombox scene, which I assumed was the big final moment where the couple gets back together (and was also the only thing I knew about the film), but then when it actually happens, it's just like, a thirty-second scene where Lloyd holds the boombox and Diane hears the music she lost her virginity to, then the scene ends and they don't actually get back together til a significant amount of time later (and not before they resolve the weird subplot where Frasier's Dad is evading his taxes).
3. Terminator 2 - "Hasta La Vista, Baby"
This is still probably my favorite action movie ever, and whether it's giddy-nostalgia or pure objectivity, I still frickin' love the "hasta la vista, baby" / gunshot / frozen T-1000 explodes scene, but in retrospect, it is a little amusing that after the most famous moment of the film -- an extremely-final-seeming one-liner where the villain gets blown up -- the villain just re-forms seconds later and continues coming after the characters.
It's a pretty ballsy directorial decision, really. It's basically the equivalent of if John McClane dropped Hans Gruber off the roof, said "yippee ki-yay motherfucker," then Hans hits an awning and bounces right back onto the roof intact and they resume fighting.
4. The Warriors - "Waaaariorrrrrrs, Come Out To Plaaayayaaaayyyyyyy..."
The most famous quote from the 1979 cult fave The Warriors (which also plays while the DVD menu loads) comes at the big climactic ending of the film where The Warriors and their rival Rogues finally square off, then the Rogues' leader draws a gun, gets a knife thrown into his arm, and the fight ends immediately when the 'head' gang shows up.
It's an unexpected but satisfying ending to a movie that has more than enough action in other parts, but it's a little odd that the banner line from the film is one character chillingly calling out another for a big final battle that never actually happens.
5. Scarface - "Say Hello To My Little Friend!"
The most-quoted line from The Film That Launched A Million Dorm PostersTM comes at the movie's big final moment when Tony Montana goes out in a blaze of glory, though ultimately, he fires the "Little Friend" and blows up a door to defeat 4 of the 75 billion goons closing in on him, delaying his "getting shot through the back with a shotgun and really violently falling into a pool" by like, twenty seconds. But MAN did he ever show those four dudes!