The gun and the beast- from Tremors (1990)
This shot is almost not worth mentioning. You could even say it's not actually an effect, it's just a bit of editing. Here's what happens: One of those giants worms that torment the city of Perfection breaks into the basement of survivalists Burt & Heather Gummer (Michael Gross & Reba McEntire). They shoot it to bits and it dies.
The sequence is comprised of a number of different shots: A full-size set with the actors shooting guns. Another full-size set with a full-size worm, capable of some limited movements. And finally a miniature set with a miniature worm, rigged for more complicated and violent movements. The small-scale set was carefully matched to the real set, so much that the effect team actually asked to have certain items removed from the set, because they knew it would be too hard to copy in small-scale. Cutting back and forth between the full-size sets and the miniature works well, because the miniature is so well-done. Once again Bob and Dennis Skotak were responsible.
This specific shot we're dealing with today is a whip pan from a gun lying on the floor to the worm coming through the wall. First the gun part was shot on the full-size set, with the camera simply panning away quickly. The same camera move was repeated on the miniature set, this time the camera pans into the set to a view of the angry worm. The two different shots were put together with nothing more than a cut. That's all.
Like I said, this is barely an effect, but it's a nice little trick that helps pull off the scene, and distracts you from the fact that the characters and the worm weren't actually in the same room.
A simple little piece of movie magic.