In fiction writing tropes, there’s the concept of the asspull: a moment when the writers pull something out of thin air in a less-than-graceful narrative development, violating the Law of Conservation of Detail by dropping a plot-critical detail in the middle, or near the end of their narrative without Foreshadowing.
As you might guess from the description, this is something supposed to be avoided since it tends to annoy the audience — or at least any audience that’s halfway paying attention. As an oft-time audience member myself, I agree, and yet, here I am in this week’s comic suddenly having Rosa using a device we haven’t seen before to do… something. What’s my excuse?
Or I guess I could say, this is something that hasn’t been directly foreshadowed but could be considered “in the toolbox” (or in this case quite literally the toolbelt). This is why we don’t throw up our hands and quit the theater in disbelief when Luke Skywalker can pilot a spaceship he’s never flown before down the Death Star trench. He drove a landspeeder, right? His father was “the best starpilot in the galaxy,” right? He used to bullseye womp rats in his T-16 back home, and does anyone watching Star Wars for the first time have any clue what a T-16 is? Nah, but it sounds right. Kid’s a natural. Roll with it.
If Frank suddenly pulls out a beeping device and starts scanning things, I’ve got a lot of explaining to do, but Rosa? For the sake of narrative shorthand, I’m making the bet here that the audience will no more question her having certain electronic diagnostic tools than they would her having a wrench or screwdriver. I’m thinking that from my point of view, that would just make sense to me based on her presentation so far. In fact I daresay the readers are properly primed to not blink if she hops into a helicopter and flies it, though they haven’t seen her doing so before. It’s her talents and resources that have been properly foreshadowed, and those can be riffed on now without having to account for every last thing, so long as (and this is important) those things wouldn’t have come in handy for solving a situation prior to this one.
Tl;dr — if you have a character who’s a cop in, say, Los Angeles, you shouldn’t need to show that they’re good at driving fast in traffic or shooting a gun (unless they happen to be really, really good) because that’s part of the presumed skillset. This is where Law of Conservation of Detail actually favors leaving those details out, and implication is enough to move the story along.