I'm not going to bother spoiler-tagging the following, but these are the bits I could make out of the trailer. Some were clearly referred to more than once:
The Ood (the
BBC site confirming the Doctor and Donna will visit the planet of the Ood)
A giant bee crashing through a window
Patricia Hodge? (Oops, sorry: too young for Patricia! Was more likely Fenella Woolgar, listed by the
BBC site as playing Agatha Christie)
Alien soldiers, laser-type weapons (which from the
BBC site photo look like [the confirmed reappearance of the] Sontarans)
3 witch type women (later about to kill someone with a knife, sacrifice style)
Romanesque group of men including Peter Capaldi (confirmed by the
BBC site as being Pompeii on the eve of Vesuvius going pop)
Earth military and UNIT soldiers
Martha
Bernard Cribbins - unclear if reprising his London paper-seller role from "Voyage"
Sarah Lancashire (who the
BBC site confirms is in Episode 4:01)
the Doctor focussed on "I want a mate"
chained up Ood
coffin/casket type chamber being opened
Sarah Lancashire with what looks like the Doctor's sonic screwdriver
the burnt-looking creature declaring itself the "pyrovire" (sp.?)(anyone watching with subtitles on???)
Felicity Kendall (confirmed by the
BBC site as Lady Clemency Eddison in the Agatha Christie episode)
a bloke that could be Martha's dad
Tim McInnerny
full-face close-up of a (presumed) Sontaran (episode title "The Sontaran Stratagem" is confirmed by
the BBC as episode four)
a priest concluding it had been an "entertaining evening" (the Agatha Christie episode, judging by period)