Visible crew/equipment: Just after Missy treads on Osgood's glasses after killing her, you can see a boom mike shadow on the wall.
Continuity mistake: When the Cyberman in the office locates Clara hiding behind the desk, its gun arm goes from stretched out to bent between shots. (00:00:46)
Continuity mistake: Missy's cameo brooch is unpinned and hanging askew when she vaporizes Osgood, but the brooch rights itself and is pinned properly when Missy steps on Osgood's eyeglasses. (00:23:00)
Continuity mistake: During the early scene with the Cybermen outside St Paul's, when Missy pulls out her phone/disintegrator weapon and shows the Doctor pictures of the Cybermen going viral all over the planet, and when she prepares to take a picture of the two of them, her grip on the device, as well as which hand she's holding it in, keeps changing between shots. (00:03:00)
Continuity mistake: When Missy orders her Cybermen to blow up the plane and kill some Belgians, her control bracelet is missing from her wrist in one shot. (00:33:54)
Revealing mistake: During the sequence where the Cyber-clouds covering Earth are burned away, there is a shot showing the clouds burning over the Sydney Opera House. The shot is, very obviously, a still image to which CGI of the burning sky has been added, with extremely unconvincing results. (00:47:37)
Revealing mistake: During the scene at the beginning where people are taking pictures of themselves with the Cybermen, there are a few moments where the Cybermen's armour is revealed to be rubber when people touch it. (00:02:45)
Chosen answer: No, no information is avalible for the identity of the entity.
Repo_Man