10 Huge Doctor Who Plot Holes Everyone Overlooks

Doctor Who often reminds us that the TARDIS' chameleon circuit - which is supposed to help the ship blend in with its surroundings - doesn't function. It's been that way since the beginning of the show, and as a result, the TARDIS is stuck in its now-iconic blue police box shell permanently.

Or, y'know, until the Doctor can be bothered fixing it.

That said, the TARDIS - though having retained its overall design - has actually changed over the years. It's got taller, its shade of blue has changed, and its windows have differed too. These changes are subtle (and we often forget about them!) but they do happen quite regularly.

So... is the chameleon circuit broken, or isn't it?

While these are obviously out-of-universe design changes, you can also head canon this into the show in a few different ways. Maybe the chameleon circuit determines the form, while the details of that form are down to the TARDIS itself. Or, maybe the chameleon circuit isn't 100 percent broken - maybe it's closer to 95 percent.

Or, if you're in a particularly cynical mood, you could view it as a plot hole.