This post contains spoilers.
The First Order’s battering ram cannon has a pivotal role in the final act of the film, ruining Leia’s plan to hide in a fortress on Crait. Finn almost dies in a last-ditch attempt to destroy the cannon, before Luke Skywalker saves the day by psyching out Kylo Ren.
On a surface level, that cannon is as narratively interesting as any other random weapon, which is to say: not very. But after reading the Last Jedi Visual Dictionary (highly recommended if you enjoy learning the name of every random alien in a crowd scene), I’m much more invested. That’s because the cannon is powered by a kyber crystal, calling back to the events of Rogue One.
Rogue One gave us a ton of thoughtful backstory for Episode IV onward. It explores the sacrifices required to keep the Rebel Alliance on its feet, and in a more subtle way, it added a surprisingly emotional and political depth to the construction of the Death Star. The Empire’s deadliest technology relied on kyber crystals mined on Jedha, representing one of the greatest struggles at the heart of Star Wars: the conflict between the Empire and First Order’s destructive attitude, and the heroes’ connection to the Living Force and the natural world.
Jedha was home to an ancient temple, providing Force-sensitive kyber crystals for Jedi to use in their lightsabers. After killing the Jedi in Revenge of the Sith, the Galactic Empire invaded Jedha’s holy city, killed most of the monks who lived there, and strip-mined the land for its resources. Its final act was to test the Death Star’s weapon on Jedha itself, blowing the place to smithereens. Beyond the space battles and personal feuds of the Original Trilogy, this storyline illustrated how the Empire’s war machine is fueled by heedless destruction of natural resources—something we revisit with Rose Tico in The Last Jedi.
The battering ram cannon is a minor footnote in The Last Jedi, but it’s a great example of how Star Wars uses background lore in a subtle yet effective way. It’s not an in-your-face callback or even an intriguing plot-relevant detail like the First Order’s hyperspace tracking technology (another Rogue One tie-in), but if you’re aware of the backstory, it really enriches your understanding of the scene.