Continuity mistake: After the TV signal cuts out due to the crash of the Titanic, when Sylvia says "It's gone dead" while searching for a channel, she moves her arm with the remote forward the same as she did in the previous, wider shot. (00:18:57)
Continuity mistake: In this episode, Rose's teeth look different than in all her other appearances. She also has a different accent, both for no apparent reason.
Continuity mistake: The house that Donna and her family are shown living in in Series 4 is different from the house the Doctor dropped her off at at the end of her first appearance, "The Runaway Bride." You would assume they'd merely moved - except that in this episode, Donna and her family are shown living in their Series 4 house before the events of "The Runaway Bride", on the day Donna gets the job that leads to her meeting the Doctor in the first place.
Chosen answer: No, no information is avalible for the identity of the entity.
Repo_Man