Destruction as a good thing
Although the Gremlins are destructive, they don't feel it is evil to destroy. The assumption in the Air Force is that order is clearly superior to chaos, but the Gremlins don't feel that way at all. In chaos, there is a balance upheld by the ways of nature. They are obedient agents of natural decomposition. They are destructive in the way a mold or a bacteria is destructive—within a balance. Destruction is seen as a good thing to be held in tension with construction.
Progress as a bad thing
Progress is a good thing, right? After all, the Air Force is using progress to fly around the skies, and what could be more exciting than that? However, the Nazis are also using progress, but in a negative way. To the Gremlins, the unintentional consequences of technological advancement are damage to the environment, so the Gremlins see all progress as negative. They want to stop progress, so they destroy machinery.
The alignment of opposing forces
The Air Force and the Gremlins are shown as opposite forces. The Air Force takes situations of chaos and imposes order, but unintentionally, they have the inverse effect on the nature around them. The Gremlins are fighting for the order of nature by destroying the Air Force's attempts at order. They are agents of natural chaos. By the end of the plot, these two antithetical forces are united into a powerful force for good in the battle against evil.
Gus as a Gremlin getter
Gus is a Gremlin getter. He gets to go and discuss the war with the Gremlins, explaining that even if the Air Force is somewhat destructive, there is nothing as destructive as a Nazi. They explain the risks of losing in this battle against evil, and before long, Gus discovers an aspect of his self that he didn't know about before. He is winsome in a heroic way; he can make friends and save the day that way, instead of doing battle, which is the standard military approach.
Rebuilding and restoring
The Gremlins have an untapped potential that the reader might be startled to discover. Just as they were used for destruction and tearing down, so also they are capable of helping to rebuild and restore the Air Force. The dilemma was a symbolic one that left the good guys even better equipped to win in their war against evil. They are able to become more powerful for having been weakened for a time by the Gremlins.
