Time and the Rani doesn’t particularly try to be realistic. To start with, it’s clearly written as a farce. Beyond that, several times it deliberately breaks the reality of the situation to (not to make it sound more sophisticated than it is) make some kind of meta-commentary about the show and the way it’s perceived. There’s the business about the Doctor being horrified at a vision of Mel’s face, and whatnot. If that’s not the 1987 equivalent of “the windows are the wrong size”, I’ll eat my left shoe.
The unreality of the thing has always struck me as rather the point. All the awful things in it aren’t so much awful in their own right as they are, on some level, a commentary on the lazy way the show is often put together. And in that, I think it’s mostly pretty on-target and hilarious.
I realize that the script was already sitting there and that Cartmel was less than thrilled with it, but the subversive, postmodern sense of humor strikes me as all him — rebelling against a by-the-numbers script that served no purpose and had nothing to say by turning those qualities on their heads. It calls to mind the “fanboy” in Greatest Show and the philosophical guard in Dragonfire, if a bit broader and less informed. More of an outsider’s perspective — which he was, at the time.
Davies does this all the time now — Love & Monsters, for instance. Which I realize isn’t everyone’s thing, but… well. Major difference is, he does it better.