Things u didn't see coming.....or otherwise jawdropping. When Yoda busted out the lightsaber. Avengers....assemble. Thanos snap.
The Alien exploding out of John Hurt's chest in the original Ridley Scott "Alien" The head spinning and explosive green vomit from the "Exorcist" The skeletons rising out of the ground in "Jason and the argonauts" Actually that whole original movie.
Well, I guess not. More dramatic versus watching at home though The whole walking out the theatre mind blown
That part in avatar in 3D at the movie theater where they are walking through all the glowing plants.
Finding out that the Bruce Willis character in The Sixth Sense was actually dead all along. Still can't believe I didn't see it coming.......
Basically the entire first LOTR movie, that shit had me on the edge of my seat as a teen. Also in the third movie when the chick stabbed the nazgul in the face after he said "no man can kill me" was awesome and gave me goose bumps.