Speaking to the Observer he said:
“That’s been a riot to do. And that’s been sort of a big fun chase episode, really. Just Mr. and Mrs. Who battling their way past nonsense and that’s been great fun. They’re lovely together, they are.
“Alex [Kingston] is always great value. It’s time we saw her back being a kick ass hero instead of playing mums and sisters and all that. It’s a waste of her.”
Moffat also spoke about whether the Sonic Screwdriver will return, and whether fans might see the one River had in her debut story, Silence in the Library:
“Well, I’m not answering your second question [about the future Sonic]! That has to be the answer to that. As to whether or not we’ll see the sonic screwdriver again, of course we will!”
Additionally, Moffat seemed to indicate he was working on Series 10 (although this was a little unclear) when speaking about what he was most proud of with the latest series:
“I’m proud that we get to the end of the series and it all looks pretty and is nice. I’m just embarking on the new one and it’s terrifying. I have to make all that again.”