When offered a restorative drink by the Sisters of Karn, The Doctor refuses, saying, "I had a little drink about an hour ago and..." He would probably continue, "...it went right to my head." Because that's the lyric of the 1925 song, "Show Me the Way to Go Home," made famous again by Julie London in 1968.
This episode was watched by 9.3 million viewers on its original transmission.