Something interesting about the first movie, explained in the extras on the DVD:

The first film actually was supposed to have a slightly more complicated plot involving the earth being caught in the crossfire between two warring space fleets. The "Bug" wanted them to go to war so that his race could feed off of the carnage. For some reason, this did not do well with test-audiences, so some minor re-edits and a re-captioning of the restaurant scene, and the plot was simplified down to one battle cruiser threatening the earth.

(The restaurant scene: Originally, those two characters were supposed to have been the emissaries from the two warring fleets, and they were going to have a peace conference over plates of pirogi.)

Frankly, hearing what the plot was supposed to be, I prefer it to the final re-edited version. Makes much more sense.