Continuity mistake: When Amy lies down on the tree stump, her hair is all over her face, but on the wide shot her hair is behind her head. (00:12:46)
Continuity mistake: After the Doctor finds out River's in Stormcage, when he pulls out of the pocket computer to look at the readings from the time crack, it rotates in his hand between shots. (00:19:24)
Continuity mistake: In the last scene, when Amy attempts to seduce the Doctor, she pulls his suspenders off his shoulders and he pulls them back on. As a result, the suspenders change position between shots.
Chosen answer: No, no information is avalible for the identity of the entity.
Repo_Man