Prior to the season premiere, press statements about the season announced various celebrity guests who were not featured in any programmes. These celebrities include Anthony McPartlin and Declan Donnelly, Liam Payne, John Simm, Emma Watson, Daniel Radcliffe, Paul McCartney, Russell Brand and Zayn Malik.
Although most episodes are numbered on the BBC website, they often do not correspond to the actual broadcasts; many episodes are unnumbered, a couple of episodes are numbered twice where a repeat broadcast has been assigned its own number, and some numbers are skipped over altogether.