Well it looks like this series arc has something to do with lightbulbs, or it could just be another Moffat red herring. But, so far, every episode has had something to do with lightbulbs either having to be changed or flickering;

Pond Life: The doctor is having to change to TARDIS roof bulb
Asylum of the Daleks: Lightbulbs flickering when the Dalek/ humans are near
Dinosaurs on a spaceship: Rory and his dad both changing lightbulbs
A Town called Mercy: again flickering lightbulbs.

I guess we'll find out if this has anything to do with the finale after next weeks episode

And it was good to see Biggs Darklighter in Doctor Who once again