a challenge and caused discomfort. The crew were concerned that the cast, particularly the three lead actors, would fall ill as their costumes were not designed for such weather conditions. Even so, the cast remained healthy. Scenes outside and inside the monastery were filmed at Caerphilly Castle, previously used in Doctor Who in "The End of Time" and "The Vampires of Venice". The actors each played their respective Gangers, with prosthetics applied to their faces for when the duplicates' faces reverted to the original material of the Flesh. Moffat wanted the Gangers to appear like "eyeball matter": white with small capillaries running through them. For the scenes in which both the character and their respective Ganger was in the same shot, a double for each of the actors was used. Most of the shots showed either the character or their Ganger speaking over their counterpart's shoulder, as only the backs of the doubles' heads were made to look similar to the actors. The episode also contains several tracks of contemporary music. In the beginning when Amy and Rory are playing darts inside in the TARDIS and the Doctor runs a pregnancy scan on Amy, the song "Supermassive Black Hole" by Muse is playing in the background. The Gangers also play "You Don't Have to Say You Love Me" by Dusty Springfield. Broadcast and reception "The Rebel Flesh" was first broadcast on BBC One on 21 May 2011 and on the same date in the United States on BBC America. In the UK, the episode achieved an overnight rating of 5.7 million with an audience share of 29.3%. When consolidated ratings were calculated, it was reported that 7.35 million viewers had watched the episode, making it the sixth most-watched episode on BBC One for the week. It received an Appreciation Index of 85, considered by the BBC to be "excellent". Critical reception "The Rebel Flesh" received generally positive reviews by critics. Dan Martin, writing for The Guardian, said that "The Rebel Flesh" "is particularly satisfying" though it seemed that not much had happened due to its being the first part of a two-part story. He praised Graham's "believable world" and "well-drawn" characters of Cleaves, Buzzer and Jennifer. He later rated it the seventh best episode of the series, though the finale was not included in the list. The Telegraph reviewer Gavin Fuller called it "a very traditional-style Doctor Who story". He