Carice van Houten and Guy Pearce became romantically involved on the set. They missed the movie's premiere at the Venice Film Festival because their son, Monte Pearce, had been born just five days before (director Martin Koolhoven nicknamed him 'the Brimbaby').
Guy Pearce admitted that he had trouble getting the accent of the Reverend right, who is supposed to be Dutch. He called it one of the hardest accents in the world, but worked hard to get as close as he could, hoping that Dutch audiences would forgive him if it did not sound completely right.
Just before shooting, Mia Wasikowska backed out of the production due to exhaustion. When one of the movie's financiers also pulled out, the movie was nearly bankrupted before any footage was shot, since the crew had already been hired and complete sets had been built. When Guy Pearce took the plane to come to Europe, he took a huge risk, because the financing was not completely in place. However, he had been very enthusiastic about his Reverend character since meeting with director Martin Koolhoven, and his presence was a deciding factor in securing the rest of the budget. Within a few days, Wasikowska was replaced by Dakota Fanning (who had already been considered for the part, but had availability problems before), but then Robert Pattinson suddenly backed out. Luckily, Kit Harington was prepared to cut his holiday short, leaving him only a few days to get to the set and prepare for filming. In 2017, Robert Pattinson admitted he had backed out, because he thought the movie would not happen, since Wasikowska had pulled out. He said he deeply regretted not doing the movie.
Director Martin Koolhoven had been preparing the movie for 5 years. When funding for the movie almost fell through at the eleventh hour, he had to go to the hospital with symptoms of a heart attack. Fortunately, it turned out to be a panic attack from all the stress.
Even though being funded internationally, having an almost complete English speaking cast and being shot in Spain, Hungary, Austria and Germany Brimstone can be seen as a Dutch production. All department heads are Dutch: the director and writer, producer, DoP, editor, composer, production designer, sound designer, production sound mixer, art director, costume designer, head make-up and VFX.
The movie's chapters would originally follow each other much faster. It was composer Junkie XL who suggested to put a few seconds of black screen in between, in order to give the audience some time to breath.
Director Martin Koolhoven was offered to make the movie for an American studio, but that would mean he didn't have final cut, so he chose to make it a European co-production, independently financed by eight different countries.