Right, especially considering they didn’t even spotlight the most interesting feature of the planet at this point: Vader’s Castle.

When everyone speculated about Kylo going to Mustafar, most people assumed it would feature him at his grandfather’s fortress. Instead, we see him fighting in a forest, something we didn’t know existed on Mustafar, and we don’t even get a glimpse of the castle. Instead, we have to learn in books that it is some kind of garden of iron trees outside of the castle? Very weird.

Especially considering much of the “Mustafar” concept art seems to be more bleak and grey, rather than red, I honestly think this planet wasn’t meant to be Mustafar, and it was changed to Mustafar later on during post-production. The fact there was also supposed to be a lake with a giant psychic creature residing inside further makes me think this was meant to be its own unique planet.

So then content like Vader Immortal and the Vader comics added elements to explain this apparent continuity discrepancy.