Chapter 5: The Gunslinger - S1-E5
Stupidity: Mando's ally breaks the fob saying he's got it memorized. Memorize a tracking device, that's new.
Suggested correction: He means he memorized the chain code, the biometric data stored on the tracking fob. Calican already knows Fennec is headed towards the dune sea so they don't need the fob to track her location.
Beyond the dune sea, is what he says, yes, which is an enormous desert on the vaste planet. Memorizing the biometric data does not help at all without the tracking device. I took it that he memorized the positional data, but if I know someone's last known location, and that they are headed "beyond the Sahara desert" it is not really helping me find them, is it? You can make a guess, of course.
The chain code is what is used to identify the target, when they are turned in to collect the bounty. You don't need the tracking fob if you already know all the numbers in the chain code. That's the part that he memorized. It doesn't appear that the tracking fob gives you precise location data, so "In the Sahara dessert" is all you get. If the tracking fob did give more precise location data then every idiot in the galaxy would be a bounty hunter.
To identify the target he has the puck already. My point is that "Got it all memorized" is a plot device that works when your target is stationary (like The Child in the first episode), not a moving target. He smashed a -tracking - device (which took it where he is now) and then says he's "got it all memorized." You can't memorize tracking, and the chain code simply includes data like the age that are of no use for a target already well known like Fennec. What he memorized was her last known location at most... which if the fobs are as vague as you mention (one hopes that they are not just beeping dowsing rods) would make even less sense, because he wouldn't have a clue about her position and course and could be off by hundreds of miles.
The chain code contains identifying information that proves what target you've brought in. In another episode a character worries that if his chain code is scanned he will go to prison because he's a wanted man. Yes, the tracking fob is used to hunt down your target but that's not why Mando wants it and why the other bounty hunter destroys it. Without the fob, even if Mando catches Fennec he won't be able to collect the bounty because he doesn't know the chain code.
If we go with this theory, it sounds like Mando wants the money (and recognition) to bring Fennec in, but he does not care about that nor he was asking for it; the fob has a different use, and the chain code is memorized separately from that anyway (he was given in the first episode tracking The Child a fob without a chain code). The chain code is simply a code with the essential information about the subject, like a personal document. If that what he memorized, it's as if he said "Don't worry, we'll find her in the desert, I got her social security number." And if he captured Fennec, which was needed alive, he would have gotten the recognition no matter what.
I tend to agree with the mistake that the tracking fob is receiving updated biometric coordinate data, so there's no way memorize updated data, at most it would be memorizing last known coordinates. However, I would advise using terms like "Baby Yoda" if you want to be taken seriously, otherwise it looks like you haven't watched the show. There's no need to use incorrect terms just because you think people won't know who "The Child" or "Grogu" is.
