1. The Daleks escape in episode 3 has caused the cracks in time. 
2. Amy Pond can't remember the Daleks because her kidself is travelling with another doctor or an older 11th Doctor. 
3. River Song will appear in the finale 
4. The Original Cybermen will return and battle the Cybus Cybermen 
5. Episode 8 and 9 are rumoured to be called 'Cold Blood' and 'The Ground Beneath Thier Feet'

6. Episode 12 of the series is rumoured to be titled "The Pandorica Opens" and Episode 13 "The Big Bang" and is rumoured to feature the Daleks, Cybermen and Sontarans and various old and new enemies. If this is true then the setting for Episode's 12 and 13 could be the Death Zone on Gallifrey as many monsters are there and this "Pandorica" somehow let's the Doctor go back into Gallifrey's past before the Time War.

7. Sally Sparrow will return in episodes 4 and 5. 
8. Rory will travel in the TARDIS. 
9. The character called the Dream Lord is either a Timelord, an Eternal or the Trickster. 
10. It is rumoured that Vincent Van Gogh will stab a yellow monster in episode 10.