Here’s a really informative and interesting interview with the filmmakers of The Ritual: David Bruckner (Director) and Andrew Shulkind (Director of Photography). Starts at 39 minutes, and is like a really good DVD extra.
The crafting of the creature scenes is discussed, and how the creature itself was brought to life in stages is also fascinating.
Lots of information about shooting at night too, and how they created the tone and aesthetic of the film. The bears, adapting from a book, what they were up against technically, and how the curious landscape and its variations were incorporated into the filming, is also discussed.
Prior to this, David and Andrew talk about their other horror films, which is also great.