Alright, caught up with the last several episodes. Assorted thoughts:
-That was a good run to end the season on. Some better than others, but I didn't come away from any of them feeling unsatisfied, which is a good step up for a series that seemed like it was starting to succumb to pacing issues and recycled plots more and more. Even Polsky turned in a pretty decent script.
-The continuity nods felt much more natural than they had been, too. That sort of thing is fine when it flows into the script and makes sense in context, and a lot less so when the reference is itself the punchline.
-It is, however, growing ever more obvious when there's a new toy to push. Merch driven series and all, but there's no way the show staff came up with those rainbow designs.
-Magic being transferable is... interesting. I'm going to assume that's an alicorn thing because it retroactively makes MMC make more sense.
-On a related note, wavy astral mane. Can we keep that? Please? I'm sure they're a pain to animate, but it completes the princess look.
-For all the time they spent in the old castle this season, nothing substantial came of the castle itself other than a sentient tome of dark magic (whose spirit is presumably still roaming the countryside, for those keeping tabs on loose ends). Did a ruined castle toyset get canned or something?
-Tirek's going to be a hard act to follow. Dangerous ability, dangerous partner, and he acquired a staggering amount of raw magical might by the end. And all that was still secondary to the rainbow friendship beam, which I'm pretty sure they can do on command now. Plus Discord's not going to pull a face-heel turn again. The next big bad's got his work cut out for him.
re: Canon: The show's writers are clearly trying to keep track of what's actually in the show, and nothing else. The comics can be fun too, but that sort of thing always amounts to officially licensed fanfiction, with the best case being that particularly popular elements migrate back into the main branch of the franchise. These things are on completely different production cycles anyway.
re: The Princesses Who Don't Do Anything: The simplest explanation is that there's little to suggest that they're exceptionally powerful in the three mundane forms of pony magic. Even a millennium of experience only goes so far.