Character mistake: In Leeds, when Donna meets Rose on the bench, in the parallel universe Donna tells Rose that she's nothing special; she's just a temp. However, in that universe, Donna was never a temp; it was a job she avoided, which created the world in the first place.
Doctor Who (2005)
1 character mistake in season 4 - chronological order
More mistakes in Doctor Who
The Day of the Doctor - S7-E16
Clara: Doctor, what's going on?
Eleventh Doctor: It's a... Uh... Timey wimey... Thing.
The Doctor: "Timey" what? "Timey wimey"?
Tenth Doctor: I... I have no idea where he picks that stuff up.
Rise of the Cybermen (1) - S2-E8
Trivia: Only eleven Cybermen costumes were built, but careful filming made it look as if there were more.
Last of the Time Lords (3) - S3-E13
Question: Why does The Master fear The Doctor forgiving him? What's he forgiving The Master for exactly?
Chosen answer: The Master knows that deep down, he deserves death for the crimes that he's committed throughout his life, and since he regards The Doctor as his arch-foe, he expects it to be at his hands. The fact that The Doctor is still willing to forgive him after everything the Master's put him through hurts him more deeply than death would.
Captain Defenestrator