Bill Hader was unaware that Bill Skarsgård can actually move his eyes in two different directions. Hader asked Skarsgård what kind of editing was done to achieve the effect in the first movie- Skarsgård, in full costume and makeup, responded by saying "Oh, you mean this?" and doing it, causing Hader to freak out.
Bill Skarsgård (Pennywise) has stated that he had more fun on set during this movie because he was actually able to talk to and hang out with his adult co-stars. Skarsgård had minimal contact with his child co-stars in Chapter One so that they would be more genuinely scared of Pennywise once they saw him.
Bill Hader was approached for the role of Richie Tozier based on Finn Wolfhard's wish to cast him in the sequel. Hader, who had never met Wolfhard, was extremely flattered that Wolfhard wanted him to take on the role.
One of Richie Tozier's character traits is his ability to do "voices" and impressions. Bill Hader is a well-known impressionist, famous for the celebrity impressions he did for years on "Saturday Night Live." With this in mind, screenwriter Gary Dauberman wrote a scene in which Richie does an impression of Al Pacino, a voice that Hader is quite good at. However, Hader requested that the impression be removed from the script because the Pacino impression was old material and he didn't feel like doing it again.
In an interview to promote Molly's Game, Jessica Chastain expressed an interest in playing Beverly. During the filming of Chapter One, she emerged as the fan favorite to play the older Bev with director Andy Muschietti, producer Barbara Muschietti and actress Sophia Lillis all going on record to say she would be their first choice too.
Continuing with the extreme coincidence of the number 27, this film is set to be released on September 6, 2019 (9+6+2+0+1+9 = 27). The 1st chapter It (2017) was released on September 8, 2017 (9+8+2+0+1+7 = 27). There's a 27 year age gap between Isaiah Mustafa (Mike Hanlon) and Chosen Jacobs (young Mike) as well as Teach Grant (Henry Bowers) and Nicholas Hamilton (young Henry).
Fans of the miniseries suggested the actors to make cameos into the movie, with the exceptions of Jonathan Brandis (Young Bill), John Ritter (Ben Hanscom), and Harry Anderson (Richie Tozier), as they've passed away.
The character Mike Hanlon is essentially the one chosen to be the look-out and call the remaining losers back to Derry. Mike Hanlon is played by Isaiah Mustafa as an adult and Chosen Jacobs as a kid. The name "Mustafa" means "chosen one" in Arabic.
The role of Richie Tozier was written with Bill Hader in mind, but it still allowed freedom for another actor to potentially take on the role. Once Hader officially joined the cast, the script was edited to tailor the role specifically for his talents.
Bill Skarsgård stated in an interview that even after filming had wrapped, he would have nightmares of Pennywise. In these nightmares he would have to battle Pennywise just as the characters in the film do.
This is the second Stephen King adaptation released in 2019, following Pet Sematary (2019). "It: Chapter One" was also the second-wide release Stephen King adaptation in 2017 following The Dark Tower (2017).
Xavier Dolan met director Andy Muschietti randomly and expressed interest about being in this film, having loved the first one. Dolan said "I'll do anything you want, be the door handle, the door knob, the curtain, whatever I can do in this film". He was later cast as Adrian Mellon.
Chastain, Skarsgård and McAvoy have starred in at least one X-Men movie. Chastain and McAvoy also starred together in Dark Phoenix (2019), marking this their third collaboration, and Skarsgård was in Deadpool 2 (2018). This is also Skarsgård and McAvoy's first collaboration since Atomic Blonde (2017).
Of the cast, only one pair of actors who portray the same character share the same hometown. The actors who portray Stanley Uris, Wyatt Oleff and Andy Bean, were both born and raised in Chicago, Illinois.
The trivia items below may give away important plot points.
It: Chapter Two is rumored to include a scene that was cut from the first film. The scene is set back in the 1600's and has Pennywise devour a human baby. This scene was cut from the film because it was extremely dark and disturbing.
Henry Bowers' fate was left ambiguous in It (2017) after he was pushed down a well. It wasn't until Teach Grant was cast that we learned that Bowers survived the fall. (Note: Not a surprise for fans of the book)