A few linguistic details, courtesy of many fine servicemembers I have known:
1. When one of your military characters says "it's just a few klicks back to the Gate", where "klick" means "kilometer", it's spelled with a K, not with a C. While "click" in that usage is sometimes spotted, it's rare and generally not considered correct, mostly because "click" is easily confused with other jargon. The word's an abbreviation of "kilometer", so it should have a K.
2. Marines do not wear "BDUs". They wear "cammies". (Yes, much of Atlantis's military presence is Marine.)
3. "Grunt" is not a general (or even derogatory) term for a soldier. It's a general (sometimes derogatory, sometimes not, depending on how it's used and who by -- much like the volatile and semantically-slippery "fag") term for a low-rank, enlisted service member, often with little to no hope of promotion past a certain point, and in practice it's only used for members of the Army. You probably mean "jarhead" if you're talking about a Marine (but if it's used by a non-Marine, it's offensive) or "zoomie" if you're talking about an Air Force member (though, again, same in-group language warning).
4. Not every member of the Air Force can be called "flyboy"; it's a much narrower word, generally referring to Air Force pilots (and no, not every member of the AF flies -- I once spent a commercial flight with an AF technical sergeant who was terrified of flying!)
5. And while I'm at it: they're spelled "sergeant" and "lieutenant", and while it's usually okay for one character to address another as "Sarge" face-to-face, although that intimates a degree of familiarity that's not always present, you only abbreviate "lieutenant" when referring to a third party: "I was talking to the el-tee". And it's mostly the same level of casual address implied by "Sarge". (I am informed that in Canada, the abbreviation is "Sarnt".) (Although
sarahq corrects me slightly in the comments.)
6. "Sir" is neutral punctuation for most members of the military; they barely realize they're doing it.
7. "Guns" are those big fucking artillery weapons. The thing you wear in your side holster is your "sidearm". It's also correct refer to it by the weapon name.
8. If you've just enrolled in the Air Force Academy, you're not a "plebe", you're a "doolie". Plebes come from Annapolis or West Point.
9. When you are on the radio, you must assume that your listener will be hearing you under static, interference, noise, and other sub-optimal conditions. You use the
NATO phonetic alphabet, particularly for numbers. (I wish the SGA screenwriters would figure this one out.) (You also don't ever say "repeat" if you didn't catch something. You say "say again".)
10. It's not "roger that", it's "roger", or occasionally "roj".
11. "Geek" is way more offensive coming from a servicemember than it is coming from a civilian. The word you want is probably "egghead", which is less offensive coming from a servicemember than it is coming from a civilian.