The language used in season two (Verbis Diabolo) is a fictional amalgam of Aramaic, Ancient Greek, Latin, and an obscure Arabic dialect called (in phonetic English) "Kan Allah Musali-Algins."The language, Verbis Diabolo was created specifically for the show by the curator of the London Historical Societies Emeritus Professor of ancient languages.
Penny Dreadful is an old term used during the nineteenth century to refer to cheap popular serial literature, and it could be interchangeable with penny blood, penny awful, or penny horrible. It means a story published in weekly parts, with the cost of one (old) penny. The main plot of these stories were typically sensational, focusing on the adventures of detectives, criminals, or supernatural entities.
The séance back-bending scene was filmed in three different segments: the first was on set with Eva Green standing on the table; the second was filmed in a studio where the actress bent her body as far back as the stuntmen deemed safe; the third was Eva bent all the way back in a contraption, the last was filmed in front of a greenscreen. The post-production team then combined all three segments into one.
As creator John Logan had never written a television series before, he did not produce a speculative script, but instead wrote the first two episodes directly. When he had the opportunity to pitch it to Showtime, he also wrote a forty-page "bible" exploring the characters and story, with the network eventually buying the show.
Sarah Greene stated in an interview, that the make-up for Hecate and the other witches' Nightcomer forms consists of several different pieces, which take several hours to apply. She stated that the breasts and genital regions are fake, and are part of the prosthetic. However, Greene forgot the instructions not to drink alcohol before putting on the make-up, as sweating alcohol would negate the adhesive used. Once while shooting in the make-up, her chest-piece fell off.