Another point about Yaz and missed opportunities. Someone on Twitter pointed out that she may well have known the two coppers murdered by Dalek-Lin. Why didn't Chibnall give her something to work with here? At the very least a moment of introspection. "I knew them, Doctor. That could have been me." And hell, could have been a wider narrative for her to get her teeth into. She could have been cold to Lin afterwards. "I know it wasn't you, I tell myself you were fighting the Dalek all the way, but those two people were my friends." and what about Lin? Where's her aftermath? She's basically forgotten about once the Dalek leaves her behind. But hey, you know Chibnall only had an hour and he had two meaningful conversations with Ryan's dad to fit in...
Imagine losing Aaron from this, and having Yaz in the Lin role? Not only would this have given Madip something to get her teeth into in this episode, but potentially a whole PTSD storyline that could have filtered into the character way beyond this. How do you deal with being held captive by a monster? How do you deal with guilt over your role in the deaths of your colleagues, even though you rationally tell yourself you had no say in the matter?
Plus this would have given the Doctor, Ryan and Graham a much more personal stake in stopping the Dalek, and given this episode was going for a 'Dalek' vibe that would have given Jodie something to get her teeth into when facing down the pepper pot, because as has been said she didn't have the whole Time War, last of the Timelords thing that Eccleston was able to channel into the encounter.