There should always be an internal logic to events in your game world. They can be complicated, but they should make sense when explained by an inhabitant of the world, within the parameters of the setting - be it magical or scientific.
This way if your players ever figure stuff out, they can be justified in feeling extremely clever. In essence, you're making your entire campaign setting a giant puzzle, where all the pieces fit together. Players may not notice at first that a dragon's periodic raids on farmland are correlated with increased military activity of a neighbouring kingdom, but when they do, and they make the connection that the dragon is in the employ of that kingdom, they'll feel very happy with themselves, and pleased to realise that your world has these sorts of details running in the background.
This is part of what makes complex worldbuilding so satisfying. Players may never get to see some of the minor details, but when they do it makes the game that much more realistic and exciting to dig into its secrets.
Commentary by memnarch (who has not seen the movie)
Ok, I think I followed that explanation. After going over it about 8 times in my head. Peace Moon Mk. 3 that fires an energy beam that rips through spacetime to blow up planets in the past? Definitely a scary weapon, even when the time travel is unintended! This feels too thinky for Star Wars for it to be anywhere close to the movie though. I've got an okay grasp of the hypothesis Pete/Artoo came up with, but I also had the luxury of time to puzzle it out. Imagine trying to follow Pete's logic in a single 30-second movie clip! Not to mention the narrative letdown about the First Order claiming they'll destroy the New Republic, then completely whiffing the shot.
Man, I completely forgot about this plot point! I almost wonder if the GM came up with this before or after Pete's complaint. On one hand, that's a heck of a thing to make fit with everything else that's happened so far, even the practically thrown lines like in #1936. On the other much larger hand, this is the same GM that actually maps out whole planets even when the players might only see a small part of it, details miniatures that get a session of use, as well as gigantic backstories for important NPCs. I think it also works pretty well as a reason for Nute not having taken over the Galaxy yet. It would be hard to secretly do that if half your stuff suddenly vaporized without explanation. What do you do with the remaining things? Sit tight and hope that was a random unlucky event? Move somewhere else and hope you aren't noticed?
R2-D2: Remember on Takodana we saw the destruction of a planetary system?
BB-8: Some of us did, but sure.
R2-D2: Light from that explosion would have taken years to reach Takodana. Ergo, the explosion must have happened years ago.
R2-D2: I posit that the system we saw explode was Hosnian, not Chandrila. It was 50 light years from Takodana, so it must have blown up 50 years ago.
R2-D2: Furthermore, Hosnian was 50 light years from Endor, where they fired the Peace Moon blast.
R2-D2: The beam should have taken 50 years to reach Hosnian. And it did. Propagating backwards in time.
R2-D2: The First Order aimed at Chandrila, but didn’t realise Hosnian was in the way, because it isn’t there any more. The beam arrived 50 years ago, when Hosnian was there.
R2-D2: It destroyed Nute Gunray’s bases on “Caldota” and “Courtsirius”. i.e. Cardota and Courtsilius in the Hosnian system.
R2-D2: Check and mate.
Zeppo: That makes so much sense! // BB-8: That’s crazy!
C-3PO: ¡Por que no los dos!