Father's Day - S1-E8
Plot hole: In "Aliens of London", it is established on a 'missing person' poster that Rose Tyler is approximately 19 years of age in March 2005 (The poster says 'missing since 6 March 2005'). This means that she must have been born prior to March 1986. However, in "Father's Day", which is dated 7 November 1987, Rose is still a baby in her mother's arms, when she should be a toddler aged approx two.
Plot hole: Nancy seems to have the unique ability to whistle with her fingers in her mouth - even though she's wearing gloves. (00:10:55)
Chosen answer: No, no information is avalible for the identity of the entity.
Repo_Man