What really cracks me up...
...is the inevitable scene where the Giant Spaceship ponderously parades though the screen, almost always from R to L, while in the background you hear this low-level rumbling (supposedly the throbbing of mighty engines).
The only Hollywood spaceship that ever actually succeeded in looking like I would expect a real alien spcecraft to look like (that is, totally disorienting and completely incomprehensible) was V'ger, in the first Star Trek movie. And no phony engine noises, just a dissonant and really eerie musical score.