Okay, very clever peeps who know this sort of thing, this has been niggling me since Christmas Day...
Why, when Dervla killed the Cyberman who was trying to delete her, did the other Cybermen decide to fall in with her plans?
Surely, as emotionless beings, they wouldn't have been afraid of death and would have continued to try and make her one of them/kill her?
Also Rosita was a bit of an anachronism with her language - I suppose that was to make us think at first that she was a companion from another time, but it grated on me.
Fab dress. All the costumes were fab, actually. As I'm currently trying to costume an amdram production of Christmas Carol from charity shops, ebay and primark, I am now tempted to sneak into Broadcasting House and nick the lot...