10 Doctor Who Secrets That Were Hiding In Plain Sight

10. There's A Hidden Dalek Language (Rose)

Just as Rose Tyler scattered the words BAD and WOLF across time and space at the end of Series 1, so too did the Daleks send their own message, using their own language.

This was an in-joke by production designer Edward Thomas and his team, who seeded this "graffiti" into various sets and props in non-Dalek episodes. It can first be seen to the right of some mannequins in a store window in the opening moments of Rose, but strangest of all is that it can also be seen in World War Three, when Jackie Tyler seeks refuge in Mickey's flat.

In the bottom corner are two large red wooden objects that look like bits of a coffee table or an elaborate magazine rack. But actually, they're designed to mimic the same Dalek graffiti glimpsed elsewhere in the series!

This graffiti made one of its last appearances in a Radio Times photoshoot to promote Series 2 in 2006, a subtle nod to the fact that the Daleks would make a surprise return in the finale.

Thomas has also claimed it can be found in most episodes of Series 1 – so keep those eyes peeled.