Lots of exposition to make sure you remember the last one. No major retcons that I noticed.
What the hell was this about? Did they get the cast together and then came up with a script on the spot? What’s the point of having a testicle-shivering amount of talent without a plot?
Goddamn fantastic cast doing jack shit to elevate this to beyond young adult fantasy for kids. Teens saving their world, that turns out to be a Fallout Vault with more incompetent people. Martin Landau and Bill Murray have a lot of fun chewing the scenery.