Nyssa is largely absent from this story, as it was written before it had been decided to make her a permanent companion and the Doctor was only scripted as having two companions.
Christopher Bailey infused the story with many Buddhist terms and ideas. In particular, he named many of the characters after Buddhist words, including the Mara ("temptation"), Dukkha ("suffering"), Panna ("wisdom"), Karuna ("compassion"), Anicca ("impermanence") and Anatta ("without self"). The Jhana Box alluded to a Buddhist meditative state of complete immersion, while Deva Loka was named for the heavenly realm of supernatural beings (called "devas"). Sanders, on the other hand, was named for Sanders of the River (1935).