Many of the forest scenes were filmed at the Fahrtechnikakademie Kallinchen near Berlin. This place is a former military testing area of the German Democratic Republic.
The tattoo on Noah's back, and in a picture in the 1986 version of the local hospital, is of The Emerald Tablet, an ancient text, part of what is known as "Hermetica", a collection of occultist 2nd Century Greco-Egyptian "wisdom texts". It describes, among other things, alchemy experiments, transmutation, and the creation of the universe. More importantly, it discusses the idea that both large and small actions are all connected and influence each other, which is a central theme of the series. Also, conspiracy theorists claim, since according to some people, the text is much older than the language it contains, that it might be from somewhere unknown, some claim aliens, some claim time-travel.
First German series produced by Netflix.
Originally the show runners Baran Bo Odar and Jantje Friese were asked by Netflix to create a series from their movie Who Am I - Kein System ist sicher (2014). They were not interested and proposed to create something new: They already had plans for a series inspired by The Missing (2014) and a time travel movie and merged both ideas to finally pitch DARK.
The symbol on the cover of H.G. Tannhaus' book is the Penrose Triangle; an "impossible object" optical illusion created by psychiatrist Dr. Lionel Penrose and his son, mathematician and Nobel laureate Sir Roger Penrose. Roger Penrose authored one of several interpretations of quantum mechanics, which Tannhaus lectures the audience on in season 3.