A major question that's been chipped away at is just how Palpatine had a huge Final Order fleet full of planet-destroying ships ready to go on Exegol, despite the fact that he fell to his apparent death three decades earlier.
We've learned that Palpatine came back through the use of clone bodies and that his followers at Exegol are the Sith Eternal. They smuggled parts in from the Sienar-Jaemus and Kuat-Entralla shipyards to Exegol to build the ships, using the "shipwrights, engineers, and slaves" who lived on Exegol.
They might have been able to build the ships and we just about buy the explanation, but how did they manage to find the UNLIMITED POWER that meant each ship had cannons that were effectively mini Death Stars?