The called shot is a mechanic used in many games to allow attackers to aim at a specific part of a target. For example, if you want to hit a dragon in the eye with an arrow (or between the damaged scales on its belly), as opposed to just hitting it anywhere. Usually, to make the called shot, you have to roll your attack roll with some penalty, reflecting the extra difficulty of hitting a small sub-part of the target. In some systems, if you miss by a small amount - possibly equivalent to rolling what you would have needed to make to hit the full target without penalty - then you miss the called area, but hit the target somewhere else.
In other systems, if you miss the called shot, you miss and you've wasted your shot. So the most vital thing to know before you make a called shot is: What the rules say.
[Reminder: Our guest commentators have not seen Rogue One. Part of the fun is seeing how their untainted impressions re-interpret the movie through the lens of our comic.]
He didn't get hit for that extra round of prep. Yay!
I could not find a trope for "Oops, I missed".
I guess Baze/Chirut are not quite as strong with the Force as Luke. They needed to have used a computer to help aim.
GM: Okay, Baze gets a +8 Aiming bonus. Roll.
GM: The rocket blazes towards the target... but the called shot misses! It hits the side of the cockpit module.
Chirrut: Is it damaged?
GM: I'd draw the scorch mark on the token, but it's too small to see.
GM: The articulated cockpit swivels to look at your position.
Chirrut: Uh oh. This sand dune will be slag in a few seconds.
Bria: Wait, it wouldn't be slag. It'd be a form of fulgurite.
Chirrut: It doesn't matter! Run!!