4Alien: Resurrection -- Ripley Makes a Perfect Shot
Alien: Resurrection got a lot of crap for its use of (bad) CGI aliens, when in fact most of the movie was done with good old-fashioned puppets and model spaceships. For example, the gruesome scene where the human/alien hybrid is sucked into space through a tiny hole in the spaceship ...
And yet Ron Perlman is still the ugliest thing in this movie.
... was done entirely on set by creating plastic replicas of the creature and then literally pulling them through a hole.
However, the coolest moment in the movie needed no puppets or effects at all. In one scene, Sigourney Weaver is playing basketball in the ship's gym when Ron Perlman and his posse show up and start giving her shit. Weaver proceeds to kick their asses and walks away -- but not before performing an impossible over-the-head blind shot resulting in nothing but net.
Wasn't this exact scene in Teen Wolf?
That's the real thing there. Originally, the director wanted to fake the shot using CGI or having someone else drop the ball from above, since he wasn't looking forward to doing 200 takes until they got one right, but Weaver insisted on doing it herself. The crew went along with it, the whole time assuming that they'd have to eventually CG a ball in during postproduction. But then, to everyone's surprise, Weaver got it on her sixth try.
In fact, in the unedited footage, you can see that Perlman almost blew the entire shot by breaking character and going "Oh my God" after the ball goes through. That's why the movie cuts away to a different reaction shot so quickly after that part.
They could have just left the original and dubbed his voice saying, "Well, that sucked."
32001: A Space Odyssey -- Zero Gravity and Trippy Effects
You probably know that Stanley Kubrick's 2001 was made in an era where CGI as we know it didn't really exist, but you're not conscious of it when you watch the movie. You take it for granted that, for instance, a zero-gravity scene could be done pretty easily. And it could -- you just computerize that shit. But in 1968?
The movie's effects are good enough that you don't think of them as effects at all. And what Kubrick didn't have in technology, he made up for with cleverness and trickery.
Reportedly, half the cast thought they were really in space.
For example, the classic scene with the astronaut taking a zero-gravity jog around the spaceship in one continuous shot was made possible not through postproduction effects, but thanks to what was basically a giant hamster wheel:
This massive centrifuge set would rotate while the camera remained fixed in one position, giving the appearance that the actors were defying gravity. And speaking of which, what about the famous shot of the pen floating inside the Pan-Am shuttle? It looks so real that most of us never even questioned how Kubrick did it.
We just assumed he had scared the pen into floating.
The same effect that today would cost thousands of dollars in CG was created with one pen, a large sheet of glass and a piece of two-sided tape. That's it. They put the glass on a frame and rotated it slowly in front of the camera. When the flight attendant goes to pluck it out of the air, it was just a matter of unsticking it from the glass.
She hasn't aged well.
Even the trippy "star gate" part at the end was made without CGI -- because, again, that wasn't a thing yet. If you've ever been to a laser show, you're familiar with the effect:
Or if you've done heavy amounts of acid.
This was achieved through something called slit scan photography, using nothing but two sheets of glass, some backlit paintings and a camera that moved backward and forward on a track. The first glass is completely black except for a small slit at the center, while the second glass has the paintings on it: As it moves, the camera records the painting through the slit, resulting in the trippy effect.