Just prior to shooting the 16th season, Tom Baker was mauled by a dog and was left with a large tear in his lip (his first thought, he claimed, was, "Now I'll be stuck with smiling parts for the rest of my career."). The wound was covered up with make-up while it was healed, but is still very noticeable throughout the season. A scene showing the Doctor banging his lip on the TARDIS console was added to "The Pirate Planet" to account for the disfigurement.
Douglas Adams concocted the Polyphase Avitron to make the Captain's scenes more interesting. For a time, he considered giving the robotic parrot dialogue like "Pieces of silicate!"
Because Douglas Adams had other commitments, he made slow progress with his scripts. Furthermore, they were too long and too complex, and Adams' inexperience with television drama meant that he had little idea of what could be accomplished within the limitations of the programme's budget.
Douglas Adams' original concept involved a planet which is being mined by the Time Lords, who use a giant aggression-sapping machine (disguised as a statue) to pacify the natives. One Time Lord becomes trapped in the statue and absorbs all the aggression, inducing him to turn against his people. He causes the mining devices to hollow out the planet and now plans to make it dematerialise and reform around Gallifrey.
The production of "The Pirate Planet" was treated to a visit by Louise Jameson, who had played Leela until the end of the previous season. Jameson stopped by to visit Pennant Roberts as well as her successor, Mary Tamm, whom she knew from their days together at the Royal Academy of Dramatic Arts.