8 Deleted Scenes That Explain Confusing Doctor Who Moments

The Mystery

When the Doctor is forced to wipe Donna's memories at the end of Series 4 finale Journey's End, he tells Wilf and Sylvia that she'll "burn up" if she remembers the Doctor, the TARDIS, or any of her adventures in time and space.

Then, the Doctor leaves in his TARDIS, which was parked right outside Donna's house. Now, it's been established many, many times that the TARDIS is incredibly loud, and that the sound of it taking off (and arriving) can be heard at great distances, even through walls. This means that Donna would be able to hear it, and as a result, it would surely trigger her memories of the Doctor, causing her to die.

So... how doesn't Donna hear the TARDIS when it takes off right outside her house, and why doesn't that noise trigger her memories of the Doctor?

The Deleted Scene

The conclusion of Journey's End was almost wildly different to the version we ultimately got. For one thing, it nearly ended with a pair of Cybermen materialising inside the TARDIS, but even before that point, another big scene was cut involving Donna.

The scene in question shows that she did in fact hear the TARDIS taking off, which solves that part of the mystery. As for why the noise doesn't trigger her memories... we don't really know. A brief flicker of recognition does flash across her face, but clearly, the sound of the TARDIS alone wasn't enough to make her recall everything.