It's been a few nights since I've finished Catch-22 and I've had a little bit of time to think about some of the issues in the novel. Of course, it goes without saying that the novel is more than merely a scathing critique on the military by Heller. I would suggest that Heller is making a fairly anti-institutional statement, in which he sees a hegemonic relationship that exists between oppressors and the oppressed that exists only through the means of ignorance. Apart from the military, it seems that the medical profession, the Church, big business and the State are all objects of Heller's attack.
I think the interesting thing about the abovementioned institutions is that they have their own kind of language that seems nonsensical to those outside the small circle of trust. As a legal practitioner myself, I am all too aware of the fact that I have become conversant in a secret language. It would seem as though these secret languages serve to empower the few at the expense of the many. Those who are not fluent in these languages have little else to do than to trust that the "experts" are providing sound advice and that they will not abuse their position of authority.