Star Wars: A New Hope
This epic scene in A New Hope is a classic part that gets rewound and paused over and over again. The scene is at the start of the movie when a Stormtrooper in the background hits his head on a low-hanging door because the actors in the uniforms apparently couldn’t see well out of their helmets.
Signs
In this M. Night Shyamalan horror movie, you don't actually see the aliens until near the end of the plot. When we first see the creature, it's through a news broadcast, and viewers paused this scene to get a proper glimpse of the grisly, gangly monsters.