Wasn't there an episode where those Ks actually blinked out because Komplex had lost contact with his soldiers?
The 'K' on the helmets comes and goes throughout the series due to animation bloopers. None of the toad fighter pilots in the first episode have it, nor does the Stormtoad who reports to the Air Marshall in that episode, for instance, while the Stormtoads on the slave ship
do. And there's a couple of shots of Stormtoads in the opening sequence of the show where their helmets lack the 'K.' Lack of a 'K' (unless it's covered by something like antennae, such as Toad Techs, the Master Toad Spy in "The Komplex Caper," and Toadborg's Navigator and Comm. Officer in "The Artificers of Aldebaran") means only one thing: the animators got sloppy. Due to how inconsistent the 'K'/lack of 'K' disribution is it's really the only logical explanation, and the simplest.
The other explanation is that Stormtoads have the 'K' while toad pilots don't, as, to be honest, I can't remember seeing any toads in Double Bubbles with the 'K' who weren't actually already confirmed to be Stormtoads (like the Stormtoads chasing Blinky in "On the Blink" who hop into convenient Double Bubbles to go after him).
And on a final note, do notice those placements of commercial breaks and possible deleted (and scripted but never animated) scenes. It sometimes makes the pacing make more sense. I notice in the first three episodes, there was cheating with the cliffhangers too: at the end of one episode, Bucky's ship is enveloped with incoming fire from the Double Bubbles. Is this the end of the Bucky and Willy and everyone else? Well, no, of course not: in the next episode, a bolt from Deadeye takes out all the incoming fire, and they manage to take off safely. Here's hoping you people in the home audience forgot some of the details in the week that's passed since our last episode...
Well, episodes of cartoon shows are typically broken into three acts, with a commercial break between each. Bucky O'Hare is no exception. The scripts all use the three-act system, and I make note of deleted scenes where applicable, but sometimes the only explanation for something that seems off is, as I said above about Stormtoads, the writers or the animators just messed up. Even compared to other cartoon shows of the period, Bucky O'Hare is rather poorly animated, likely due to Sunbow Productions being a relatively small animation company without a very big budget, so animation bloopers are likely to be pretty frequent - for what I consider to be the most glaring, check out "The Warriors," where at one point they accidentally have a Samurai Lizard ship where a toad ship ought to be, and at the end aboard the Samurai Lizard ship where the Air Marshall inexplicably gains a Stormtoad co-pilot despite the fact he shouldn't have one, due to having been fired and severed from the Empire's payroll (and besides, he boarded the ship by himself and was shown to be completely alone in the cockpit up until that point, so he shouldn't
have a co-pilot, period, let alone a Stormtoad one!).