This episode doesn't even try to frame its events in some way: Darkwing just tells us, hey, kids, now for something completely different! This takes place three hundred-years ago, when there was a pirate version of me! Let's check out his shit. I may be paraphrasing. Nothing intrinsically wrong with a whimsical change of setting like this; it's just that in practice, it often leads to laziness, as the writers, not feeling any need to dig at all deeply, just rely on the laziest of genre tropes. To use an analogy that no one will get, it's why Startropics is a better game than Startropics II. It's also summed up in this classic Onion short.
Past Darkwing is named--well, what the title says, and I immediately got hung up on that: why "doubloon?" What do doubloons have to do with anything? Well, clearly, the answer is that "doubloon" is an old-timey word, and this is an old-timey setting, QED. Not the show's most brilliant moment, surely. But that's neither here nor there. The episode as a whole is almost a redux of "Just Us Justice Ducks," but not quite: it does feature Megavolt, Liquidator, Bushroot, and Quackerjack working under Negaduck, but as for the good guys, there's no Morgana or Neptunia. They're replaced with plain ol' Launchpad and Gosalyn. Man…I actually liked Neptunia, but do we get to see her again? Nooooo…we're stuck with the craptastic and instantly forgettable Stegmutt, whose name I always want to mistype as "Smegmutt." We do get Fenton (unrecognizable except by voice when he's not wearing the Gizmosuit), but as much as I love Ducktales Fenton, I'm pretty disillusioned with the DW version. I would also note that apparently his secret identity is common knowledge to everyone in seventeenth-century-DW-world.
I guess I haven't said much about the plot itself. Once again, I just don't find it that memorable. The characters clash, but none of them really get a chance to shine or show off their idiosyncrasies. I need a really good episode to come up in the near future, so I can remember what it is that I like about this show. It's true that it's never exactly egregiously dumb in the way that the worst Ducktales episodes are, but it is too-frequently lazy lazy lazy.