When it came time to work with Carrie-Anne Moss, an unexpected dynamic occurred on set between her and the lead Adelaide Clemens. At base camp, Moss was pleasant in her conversations with Clemens, but once they both arrived on set, Moss changed. As Adelaide Clemens describes, "She ceased any contact and kept a two meter distance from me. I did not fully realize this distancing until we started shooting; she came over and put her hand on my chin and I've never felt a more intense invasion of personal space. I just shuddered. It was fascinating and powerful."
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.
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.
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.
Roger Avary was originally set to write the film and had actually begun writing a draft when he was sent to jail for gross vehicular manslaughter and two felony counts of causing bodily injury while intoxicated. The film was then delayed until the studio hired Michael J. Bassett in Fall 2010 to write and direct.
Christophe Gans was approached to reprise his role as director and stated that although he would like to return to the franchise, he was committed to an adaptation of a another movie based video game Onimusha which prevented him from participating.
Carrie-Anne Moss had to shave her eyebrows for the role of antagonist Claudia Wolf. According to the filmmakers, this was done so that her expressions would be more difficult to tell just like her game counterpart.
Although being the same age as Heather / Sharon during the shooting of Silent Hill: Revelation, actress Jodelle Ferland, who portrayed Sharon, Alessa and Dark Alessa in Silent Hill (2006), was never contacted to reprise her role as Sharon, due to Bassett wanting the older version of Sharon to look more like her game counterpart, and less like the first film's version of her. Because of this, Sharon's teenage version bears very little facial resemblance to her child appearance.
Heather's on-set outfit consists of a stunning amount of layers. Aside from a presumable set of underwear, she wears a white undershirt and dark purple athletic pants, a paint-splattered tank top and a dark purple rubbery skirt, an orange hoodie, a cream leather vest, an olive green jacket, and a red and black plaid coat, making a total of seven layers.
In the school corridor in the trailer, just after Heather bumps into Vincent, on the wall behind them is a poster for a graphics class with a picture of a girl with a butterfly/moth over her face. Moths/butterflies are used often as imagery in the video games and represent Sharon's "change" into Heather.
7 characters return from the previous film although Sean Bean, Deborah Kara Unger, Radha Mitchell, and Roberto Campanella (4 actors) are the only actors to reprise their roles from the previous film with Jodelle Ferland being replaced with Adelaide Clemens and Erin Pitt for Sharon Da Silva, Alessa Gillespie, and Dark Alessa.
Despite claims to the contrary made by writer/director Michael J. Bassett, Silent Hill: Revelation has been noted as exhibiting multiple retcons and continuity mistakes in relation to the original Silent Hill. Many of these errors occurred due to Bassett trying to force the film series to more closely match the canon of the games, while others seem to have no real reason for being there. However, Bassett stated multiple times before the film's release that it would not change anything in the first film's continuity, and would be a "sequel first, adaptation second".
Bassett made several statements to the series' fans before the release of Revelation that later were discovered to be untruthful. In one instance, he claimed there would be no retcons between the two films, despite a version of the script from months before he made that statement showing that almost the entire continuity of the first film had been changed. In another, he stated on his blog that the Order and the Brethren were two separate cults, which was proven incorrect in the final film. He also repeatedly stated that he would be changing things from the game to match the film's canon, calling Revelation a "sequel first, adaptation second". However, Revelation changes much of the continuity of the first film in favor of moving the canon towards that of the game series. Similarly, Bassett denied that Vincent was Heather's boyfriend when asked about it, saying that is the wrong term for them. However, he refers to Vincent as her boyfriend in the DVD / Blu-ray commentary. Bassett's motives for making these statements are currently unknown.
Adelaide Clemens stated in an interview that out of the 3 characters she portrayed (A younger Heather, Heather, and Alessa) that Alessa was the most difficult to act as, saying it was like an "exorcism".
Before filming began, Bassett was open to suggestions in casting the woman to play Heather, allowing fans to post the names of actresses on his blog that they believed could play her, provided that the actress could realistically portray an eighteen-year-old and had experience in other films. Adelaide Clemens was eventually chosen for the role of Heather, though no one had suggested her. Bassett made another post asking for suggestions for Claudia's actress and some fans suggested Donna Burke, but Bassett was disappointed by the suggestions, feeling it was not a "very imaginative selection", and removed the post.
Erin Pitt, who played the triplicate roles Jodelle Ferland played in the first film, had her face photoshopped onto any old photos from the previous film featuring Ferland. Her face is also carefully obscured when she appears in the film as her characters except when playing Dark Alessa due to wearing makeup regardless.
The teenage version of Dark Alessa is based off the "Memory of Alessa" boss character from the game the film adapted, Silent Hill 3; However, both characters serve very different purposes. Dark Alessa is that of Alessa's wrath and hate while the Memory of Alessa is that of suicidal ideation.
The last scene of the movie when Heather and Vincent are leaving Silent Hill, the truck driver who picks them up is Travis, the main character of Silent Hill: Origins, a prequel game. Also the bus with two police cars escorting it is a tribute to another Silent Hill game, Silent Hill: Downpour.
In one draft the FBI-agents actually caught Heather but where killed when the police station turned into the Otherworld. In the same draft the Missionary was Claudia's henchman rather than Claudia and was a male. Red Pyramid killed it with it's bare hands rather than through decapitation and Claudia was stabbed to death. After killing Claudia and the Missionary Heather tells Red Pyramid that he is free and Red Pyramid would crumble to dust. This script also replaces Christabella's role in the first film with that of Claudia and Leonard, who are shown to instead be the instigators of Alessa's burning, while Christabella is never mentioned at all. Other notable additions are that Heather chases Alessa at several points, the Janitor from the first film would appear at Heather's school, in Jacks Inn, it would be implied Heather and Vincent have sex. Dahlia also died at the end and when Heather removed the seal from Leonard he did not die but simply turned back into a blind old man again.
It is not until exactly an hour into the film that Malcolm McDowell makes a proper appearance and even then his screentime amounts to a total of 3 minutes. Despite this he gets prominent billing as part of the cast.
The scene near the climax of the film where Harry decides to remain in Silent Hill to look for Rose is an homage to Silent Hill 2 where James Sutherland heads to Silent Hill to search for his wife Mary Shepard-Sutherland.
In the original script, when Heather returns home, Harry dies, killed by the Order. However, he is apparently "revived" in the Otherworld like a ghost, while dead in the real world. In the final version he is instead kidnapped by the order.
The mannequin storeroom scene happened earlier, occurring immediately after Douglas is killed by the Missionary. This makes more sense because the mannequin storeroom is in the mall. The Mannequin Girl is the same girl who teased Heather for her unfashionable clothing and the character of Suki is added. The final version loses this irony.
Although her father's handgun is Heather's primary weapon of choice, she only uses it twice in the whole film. She kills the lobotomy creature with a headshot and attacks the monstrous transformation of Leonard with the gun.