In an episode discussing fictional and mythic heroes I loved what I am convinced was a very deliberate Bat symbol mixed amongst the calculations on the chalkboard at the start. Certainly it was disguised but it seemed much more than coincidental. Nice inclusion of the picture of Patrick Troughton as Robin Hood. Capaldi’s brogue seems to be giving Jenna more and more confidence and licence to relax into her Lancashire accent.
By the way, as a general point, I haven’t spotted this referred to elsewhere, but do we think the new Tardis design is a nod to the one at the start of the McGann TV movie? That armchair seems very reminiscent of the one we saw Sylvester McCoy relaxing in. It could be my poor recall though, and I haven’t had chance to go back and compare and contrast.