It is an odd two parter, isn't it? Moffat has said he wants to play with audience expectations about story length this year. It does feel more like a story with a sequel presented immediately rather than a year later as might have been the case previously.

As with many things, I wish they would take a little more effort over this kind of thing, but I have to acknowledge it's mostly irrelevant to the story.

I would agree. I think new Who sometimes has an unnecessarily low opinion of its audience, particularly when it comes to historical and scientific detail.