First off, the thing with the TARDIS malfunctioning; I know it's randomly done strange things like taking on a mind of its own, but it's surely either Missy or John Simm's Master who is behind this, as probably a tactic to trick Nardole into letting her out to go on a ride.
And this will probably have a pay off in the next couple of episodes.
The fact that the Victorian astronauts were sent by Queen Victoria herself led me to believe that there was some connection with Torchwood. They seem to have been forgotten by the show since the end of Series 4, but it's hard to ignore as she SET UP Torchwood herself. I wonder if they will recur in the series finale, and also the character who appeared on the screen at the end.