The tags theimpossibleastronaut, nameofthedoctor, and timeofthedoctor should all be reformatted to follow the standard convention of hypens in place of spaces. So, I would change them to the-impossible-astronaut, name-of-the-doctor, and time-of-the-doctor respectively.
Something else to consider is to drop "the" from the first tag, since other tags seem to be written that way (e.g. day-of-the-doctor).
The first two are only used once, so a simple edit will work (though I don't have the required reputation to do it myself). timeofthedoctor has a handful of questions, so it might be better for a mod to fix that using the merge tool.