Matt Smith's final episode as Doctor Who saw both him and former assistant Karen Gillan wear hairpieces, the show's writer Steven Moffat revealed.
The Scottish actress made a brief appearance as Amy Pond at the end of the episode as viewers saw Smith bow out as the time lord and hand over the controls of the Tardis to Peter Capaldi.
Smith had to wear a wig after having his head shaved for his role in Ryan Gosling's film How to Catch a Monster, while Gillan had her hair cut off for the Marvel sci-fi film Guardians of the Galaxy.
Moffat said: "They're very good wigs but they're both wigs. Though in Karen's case that's her own hair. That wig is made of her own hair, it's just detachable now. When they cut her hair they made her a wig of her own hair. Didn't she look lovely?"
The show's writer also praised Smith's "heartfelt, brilliant and ancient" performance as an ageing Doctor was perfect, saying: "It's an end of an era, he should talk that way. You need a combination of huge sadness and lucky it doesn't end here".