Although that bit about series X being technically correct (since BTE was series 9) is wrong, since in BTE they mentioned that series 9 had already aired, making BTE series 10 and this series 11
But wasn't the statement that series 9 had already aired made as part of the joy squid's hallucination anyway, so can't really be considered to be true?
Oh, yeah that is a good point. I'd actually forgotten it was all a hallucination, probably because they already did that idea 20 years ago
On the plus side though, at least it airs before the end of the world.