Red Pyramid is a full body costume that was blended at Roberto Campanella wrists, requiring only 25 minutes of preparation for each scene, as opposed to the three hours it took in the first film.
For the scene of the goldfish "dying", the crew placed the fish in specially prepared water that would cause the animals to fall asleep, creating the appearance of a dying animal without actually causing them any harm.
Kit Harington admitted trying to play the Silent Hill games for research but quit because they were too scary for him. However, he also added that he didn't need to play the games, as his character bears very little relation to his game counterpart.
To appear blind as his character, Malcolm McDowell had to wear white contact lenses, something which later led to eye problems for the actor.
All the monsters in the film, with the exception of the Mannequin Spider which was completely CGI, were practical effects done on set with stunt performers portraying the creatures. The creatures would later be enhanced with CGI effects.