The interesting thing is that most people forget about the first set of headlights altogether, but it is what makes the second pair of lights strange and fantastic.

Spielberg does the same thing in the first Jurassic Park movie.

Knowing that the Tyrannosaurus rex's vision is based on motion, the Sam Neil character throws a road flare off into the distance so that the T. rex will follow the flare away from kids it's attempting to eat. It works.

Shortly after this, Jeff Goldblum's character tries the same thing. He waves the flare to get the dinosaur's attention. The T. rex chases Goldblum. Then Goldblum throws the flare off to the side expecting the monster to follow—it does not. It never misses a step and continues after Goldblum.

This creates a tension in the audience because we know what was supposed to happen and how it went wrong.

They use this kind of invisible ink in Pixar's Finding Nemo. The tough fish has a plan to escape the tank where they are kept. As he tells the other fish his plan, the filmmakers show us exactly how the plan is supposed to work, so that when it later goes wrong the audience knows where and how the plan derails.

This creates a kind of wonderful anxiety in the audience members. They bite their collective nails as they follow along and the plan is carried out. Will it work?

When I was a kid, I read a lot of magazines and books about special effects, and whenever they showed a photo of a miniature they would place a quarter or some such object next to it so the reader would have a sense of scale. One could see just how small the model was because we all know the size of a quarter.

This is akin to how the first two pigs are used in "The Three Little Pigs" story. As I said earlier, it is the failure of the first two pigs that allows us to measure the success of the third. In a sense, we have scale—things to compare.

We know how strange and unusual it is to have headlights float up instead of going around a car.