 To create the effect of the Angels rocking the TARDIS Mulligan and Robertson threw themselves around the ship 's set . The camera 's operator then shook the camera in the opposite direction that Mulligan and Robertson threw themselves . The scene wherein the Doctor talks to Sally via a DVD extra was created by writing a conversation , removing Sally 's lines , then having David Tennant record his lines . Moffat felt that this one @-@ way filming made the performance more convincing . Moffat initially wrote placeholder dialogue in the script for the scene where the Doctor tells Sally that he can hear her in the DVD shop , because he knew the lines that appeared would have to play " double duty later on " and be authentic and fresh both times . Gold called the sequences " the heart of the Chinese puzzle " . 
