10 Times Doctor Who Accidentally Filmed Things You Weren’t Meant To See

For their first proper outing as time traveller and time travelee, the Doctor and Donna visit the day that Mount Vesuvius turned Pompeii into a giant museum exhibit.

While hanging around the doomed city, our heroes discover a plot by the alien Pyroviles to use the volcano's energy to convert the entire planet into their new home.

In a heartbreaking scene, the Doctor and Donna can stop this process, but only by causing Vesuvius to erupt.

The Pyroviles' whole thing is that they're made of molten rock. They need to live in a warm environment otherwise they'll die, so how they survived the freezing innards of Vesuvius is a total mystery.

Confused? Well, as the Doctor and Donna are walking through the tunnels underneath the volcano, something curious happens. When they breath out, you can see their breath, as if they're somewhere very cold.

Parts of this episode were filmed in the UK towards the end of 2007, so David Tennant and Catherine Tate were presumably quite chilly in these scenes, which explains this amusing little detail.