The "feces" used in the film was a combination of cocoa powder, vegan condensed milk (because one of the actresses in the centipede was vegan), and crushed ginger biscuits (for texture). The concoction was apparently so delicious that members of the cast and crew were snacking on it on set.
When Tom Six was promoting Human Centipede - Der menschliche Tausendfüßler (2009) and starting to write the sequel, people would ask him about his idea from the first being copied in real life. This inspired him for the sequel.
Tom Six shot "Full Sequence" in colour, but was later told he had to change it to black-and-white due to being too gory.
Martin (the main villain and lead) only says one word in the entire film.