Even though Star Wars: The Rise of Skywalker pushes the franchise in a new direction with characters like Rey and Kylo Ren finding their place in the galaxy, it also celebrates the past with a lot of recognizable faces, key Easter eggs, and important plot points resurfacing for the end of the sequel trilogy. And the movie itself kicks off in a major location that fans have seen before, even if they don't immediately recognize. But it all makes sense in the context of Darth Vader's journey, as Ben Solo seeks to follow in his grandfather's footsteps.
The opening scene of Star Wars: The Rise of Skywalker sees Kylo Ren attempting to track down the location of Emperor Palpatine, aware that the Sith Lord poses a threat to his control of the First Order and eager to put down any perceived rival to his power. And that journey takes him to the planet Mustafar, where he slices through a group of cultists with the aid of a squadron of Stormtroopers.
While the movie doesn't make it clear that he travels to Mustafar, it is confirmed in the book by Lucasfilm Story Group executive Pablo Hidalgo, Star Wars: The Rise of Skywalker: The Visual Dictionary. The book declares that Kylo Ren travels to the planet that is home to Darth Vader's castle, the same location where Obi-Wan Kenobi disfigured his former Padawan and left him to die — only for Anakin Skywalker to be transformed into the mechanical monster who haunts the galaxy in the original Star Wars trilogy.
As the book states, "Kylo soon outpaces his Stormtrooper escorts as he cuts a swath of destruction through the Alazmec who attempt to block his path to Vader’s castle — or rather, its crumbling ruins. Kylo enters the castle grounds with purpose, and finds an ark containing an artifact that will lead him to answers."
Some fans might be confused about the presence of the forest on Mustafar, as the planet from Star Wars: Revenge of the Sith and Rogue One: A Star Wars Story was mostly recognizable for its rock formations and large rivers and lakes filled with lava. But apparently the Alazmec "planted a thin forest of irontrees … in a futile attempt to reinvigorate the glen that covered the land centuries earlier."