GB Spoilers For Series 5
Some tidbits from a poster on GallifreyBase
Episode 1: The Doctor gets handcuffed to a radiator.
Episode 2: Hardiman plays a character called 'Hawthorne' and Sophie Okenedo, 'Liz Ten'.
Episode 3: The Daleks have an Oblivion Continuum as a power source, whatever that is.
Episode 6: The Doctor has obviously seen 'The Wicker Man' film as he alludes to it.
Rory's surname is also Williams. I wonder if he's got a Welsh cousin named Rhys by any chance.
There's a Winter/Spring BBC trailer that shows the 'trust me, I'm the Doctor' clip at the end as well, so it could be late March/early April for Series 5.
Apparently Alex Kingston has been spotted on set again. Maybe she's back for the finale.
These should be taken with a pinch of salt though,