According to the DVD info text, it was decided at one point that all on-screen actors had to wear makeup, including the Dalek operators, who (it was feared) could conceivably be seen through the mesh of the props. The operators, in protest, one day dressed up their Daleks as women, and Michael Wisher and Roy Skelton, playing along with the joke, provided suitably "camp" voices for the dolled-up Daleks.
Although not generally recognised, this serial continues the storyline begun in Frontier in Space: Episode One (1973), essentially making this the second half of a single twelve-episode story arc.
Because Terry Nation had not written for the show since 1965, he initially believed individual episode titles were still being used - a practice which had actually been dropped after The Gunfighters. His scripts were thus titled "Destinus" (Nation's original name for Spiridon), "Mission Survival", "Pursued", Escape or Die", "The Day Before Eternity" and "Victory." (INFO: Planet of the Daleks)
This serial is considered by most reviewers to be a virtual rewrite by Terry Nation of his first Dalek story, The Dead Planet (1963).
Given the requirements of this story, the three remaining Dalek props from the sixties were deemed insufficient and seven wooden extras were built for this story. They looked pretty impressive, but were completely static (which may explain why some of the Daleks in this story do not seem to notice intruders at close range). For the next fifteen years, these were used as large parts bins to hold up the decaying remains of the original props from the sixties (which by this story were ten years old); by Resurrection of the Daleks: Part One (1984), the four props used were nearly all wood. It wasn't until Revelation of the Daleks: Part One (1985) that new, fully working props were made. Curiously, brand new props were also made for Remembrance of the Daleks: Part One (1988).