Based on one of Stephen King's longest novels, at 1138 pages. The length derived from King's desire to have all his favorite monsters in one place. King remarked that if he'd written the script for It (1990), it would have been a 32 hour miniseries. It's also King's last monster oriented story to date, as well as the last about traumatized children. This book gave him writer's block, a rare thing for King.
Tim Curry was reluctant to take the role of Pennywise initially because he didn't relish the thought of being buried under so much makeup. When he played Darkness in Legend (1985), it was a difficult and demanding role, and the hours in makeup was still fresh in his mind. To compromise, Tommy Lee Wallace minimized the amount of makeup on Curry, and a lot wasn't necessary anyway because Curry's performance was so strong.
Jarred Blancard (young Henry Bowers) hated having to call Marlon Taylor (young Mike Hanlon) a "nigger", and would often apologize to him before and after filming for his character's excessive use of the slur.
To get the effect of "It" moving through the pipework, a dolly crane was built and pushed through the piping. It was a difficult shot to get right because it was so cramped. It was also done from "It's" point-of-view because Tommy Lee Wallace believed that what we imagine is often scarier than what we see, a trick he learned from his old mentor, John Carpenter.
When Beverly goes back to the house she grew up in, Tommy Lee Wallace wanted Annette O'Toole alone on the street, without any other actors or extras around to make it creepier. Also, when she meets Mrs Kersh, he filled the scene with incidental details to illustrate to the audience that there's something wrong in this house, e.g. her teeth are all rotten, just like Pennywise's.
When Beverly is listening to the voices in the drain, one boy identifies himself as Matthew O'Connor. Matthew O'Connor is also the name of the Supervising Producer of the film. A girl in the drain identifies herself as Vicky Burrows. Victoria Burrows did casting for the movie.
The blood oozing over Georgie's photo was quite unusual to see in a TV movie in 1990. It (1990) paved the way for TV movies and mini-series in the future to push the envelope far more than ever before.
Pt 1 was the fifth highest rated program on Sunday, November 18th, with an 18.5 rating and watched in 17.5 million households. Pt 2 was the second highest rated program on Tuesday, November 20th, with a 20.6 rating and watched in 19.2 million households.
When Pennywise appears as a ghostly image in the sewers, Tommy Lee Wallace originally wanted the roots growing down to begin writhing around him, something Eddie hopes they wouldn't start doing. The budget didn't allow it, however, and Wallace thought the effect they had to use instead was rather cheesy to look at.
Stephen King's novel IT is connected to his Dark Tower universe. The novel has an image of a turtle supporting the earth. A poem explaining this, "See the Turtle of enormous girth/ Upon his back he holds the Earth," appears in both IT and the third Dark Tower novel, The Waste Lands. That book also expands on the idea of multiple dimensions, each guarded by an animal avatar, held together by the Dark Tower in the center, rather like the spokes of a wheel. The final Dark Tower novel, The Dark Tower, features a character named Mordred who, like Pennywise, shifts from human to spider form, and another character, Dandelo, who, like Pennywise, has "deadlights" behind his eyes that will drive a mortal to madness. The character Mike Hanlon appears in both IT and Insomnia, which introduces Dark Tower character Patrick Danville.
The asylum orderly, Koontz, drops a roll when he sees Pennywise. Though not covered in the movie, the book explains that Koontz uses quarter rolls to beat the patients as it is as effective as a baton and more compact.
When Beverly, Ben and Eddie hug Bill outside the hotel, it was Harry Anderson's idea that Richie doesn't hug him. Tommy Lee Wallace wasn't sure about that idea at first but later came to agree with it because Richie had become the cynic of the group now that Stan was dead.
The Chinese restaurant scene was Richard Thomas' favourite scene in the movie. It was filmed in three days. There were puppeteers under the table working Pennywise's fortune cookies. The scene was shot on a handheld camera to make it scarier.
The adult actors had to be careful what they touched during the sewer scenes because the place was so rusty, there was a very real danger of tetanus infection. Because of that, it was not a fun scene to film.
Tommy Lee Wallace wasn't sure about turning Audra from a heroine coming to rescue Bill into a victim who needs to be rescued by Bill. He didn't think it worked dramatically in the movie, or the novel for that matter.
When the typewriter types out "He thrusts his fists against the posts and still insists he sees the ghosts" over and over, that's probably an homage to Jack Nicholson typing out "All work and no play makes Jack a dull boy" over and over in The Shining (1980).
At one point, while running from Henry Bowers and his gang, Richie Tozier, (played by Seth Green), accidentally bumps into the school's principle (played by William B. Davis). A few years later, Green portrayed a secondary character in Episode 1x01 of The X-Files (1993), while Davis played the recurring role of The Cigarrette Smoking Man, the show's main villain.
The trivia item below may give away important plot points.
The spider at the climax was a fully operable puppet. It was the last scene to be filmed. John Ritter was disappointed that the final battle had to be fought with a puppet and not Tim Curry, because he felt Pennywise was the real villain of the show, and not some fake spider. The novel's ending was also much too cerebral to tackle on a television budget. Tommy Lee Wallace also felt disappointment with the movie's ending. The way he imagined it was different to the way it turned out, because they didn't have the money to do it as it was storyboarded.