The scenes we saw filmed were first, Elyan and Leon riding in hell for leather, dismounting and running inside. This was mightily amusing for the terrible Sir Leon-a-like, who didn't look like Rupert at all, although Elyan's riding double did ok.
Then we got Gwen coming out and looking after some distressed peasants - probably some kind of Camelot refugees. This was the first time for me seeing Gwen's new dress and I like it a lot! Much nicer than the bodice type dresses she's had recently. More in period keeping.
Then we had a bunch of guards lining up again and again in order to composite a huge great line of them in post-production. They had to keep moving along, on two sides of a corridor made up of blue rope. Then we had a bunch of peasants (who I assume were refugees) coming along the ssame marked corridor previously made up of guards. I think a huge line of peasants may also be composited, but this was a little harder to make out.
Then around the same time we had a quick glimpse of Bradley and Colin heading up to film in the corridor above the banqueting hall which you aren't allowed in - and Colin was in Old Merlin make up! I missed Bradley but have a couple of shots of Colin.
Later on, J. overheard a little of an episode read-through that was being conducted in a newly convened Meeting Room, and we're pretty sure they were going to film Old Merlin in the village after 6.00pm.
There's probably more but I'm knackered and can't think :) My pics are here.