I’m searching for a pretty specific documentary - I remember that it discussed The Force Awakens, specifically the building of the hallways from Starkiller Base. It’s not on my Blu-ray special features at all.
JEDIT: All I’ve been able to find is this Wired article about the hallways:
https://www.wired.com/2015/11/star-wars-first-order-base/
https://milnersblog.com/2015/11/22/the-force-awakens-blueprints/
Perhaps this was a case of misremembered medium.