Actually, according to episode 7 they're all wearing pants that only look like panties.
What does that even mean??
Apparently it's the equivalent of putting boxer shorts over briefs.
It's quite clear from watching it that they're wearing only panties (or swimsuits in a couple of cases). However, they call them pants instead of panties. This seems likely to either be an attempt to make it seem somehow okay for girls to run around with no pants on, or it's a case of using the British meaning of the term pants (which is underwear) rather than the American one.
In the original Japanese, the word they use is zubon (trousers), so, by the standards of their world, they're properly clothed.
There are never-ending rumors as to whether or not Chuck Yeager endorses the show, hates the show, or is even aware of the show's existence, from various photoshops to Facebook encounters.
According to the guy responsible for research and setting of the franchise, Gen. Yeager has been notified of the show before it was release through a mutual contact within USAF.
There is one witch that wears pants, but her historical counterpart went into battle without pants.
Cash Cow Franchise: Strike Witches more or less completely saved GONZO financially, to some extent, although GONZO has since declared bankruptcy. Furthermore, it's probably going to be the only the last GONZO animation to receive any consistent memetic fanbase in addition to Saki.
Or have a "Funny Aneurysm" Moment when one realizes that a high-class, well-mannered yet haughty and stuck up, flower loving Perrine and a somewhat ruthless, loss-of-a-loved-one-traumatized Minna are voiced by Shinku and Suigintou respectively.