Rob Zombie originally stated he would never do a sequel to Halloween (2007), until the studio decided to make it. Then he signed on to write and direct, because he didn't want someone to ruin his vision.
Daeg Faerch filmed scenes reprising his role of Young Michael Myers but was replaced and the scenes reshot after it became apparent that Faerch had noticeably grown up since the last installment and no longer looked the same age.
Kristina Klebe knew both Robert Curtis Brown (her father in H2) as well as Nick Mennell (her boyfriend in the first Halloween (2007)) before shooting. Rob Zombie had no idea and all the casting was random. Though when he told her about casting her boyfriend in the first film he said he was looking at a few people but he needed someone who could match her height.
Whether intentional or not Margot Kidder plays Barbara Collier in this film, a character with a similar name to her Black Christmas (1974) character Barbara Coard. Rob Zombie has stated that the original "Black Christmas" is one of his favorite horror films.
Character actor Richard Brake garnered his role as coroner's assistant Gary Scott based on a personal recommendation to Rob Zombie from Sid Haig. This lead to Brake being cast as Doom-Head in Zombie's film 31.
(at around 1h 5 mins) When Laurie and her friends arrive at the concert, the band is playing a song called 'Terror Train'. Terror Train (1980) is the name of a horror movie starring 'Jamie Lee Curtis', the original Laurie Strode.
In the scenes shot at the exterior of the hospital parking lot, the location of the emergency room entrance to the hospital was actually the entrance to the Spinal Cord Injury Clinic at the now-defunct Sepulveda Veterans Administration Hospital in the San Fernando Valley, California.
Rob Zombie was not comfortable shooting the first Halloween (2007) in the 2.39:1 aspect ratio, as he was used to the flat 1.85:1 frame that had accompanied his previous films. For this film, he chose to shot the whole picture on 16mm, rather than the traditional 35mm, and he returned to his preferred 1.85:1 aspect ratio.
Jeff Daniel Phillips plays two completely different roles in the movie: Howard Boggs and Uncle Seymour Coffins. He is only the third actor to ever play two different roles in the same film in the either Halloween series (the others being Nancy Kyes) and Danielle Harris). Dick Warlock actually plays three different characters, "The Shape" (Michael Myers) and Patrolman #3 (the one that hits the Michael lookalike with his patrol car) in Halloween II (1981) and "Assasin" in Halloween III: Season of the Witch (1982).
(at around 41 mins) Laurie has a picture of Charles Manson over her bed. Later (at around 57 mins), after Lynda's father tries to kill Loomis, it is revealed that the gun was not loaded - just like the gun Manson follower Lynette Fromme pointed at President Gerald Ford.
Jesse Dayton recorded an album as Captain Clegg, the album was produced by Rob Zombie and released on August 18, 2009. A music video for the song 'Zombie A Go Go' was directed by Don Swaynos and released online, while several other videos, directed by Zombie, were included on the film's DVD / Blu-Ray release.
Betsy Rue who plays Jazlean was actually given the role during a reshoot as a favor to Rob Zombie to Rue. Originally for Halloween (2007) Betsy was given the role of Lynda but had to drop out of the film due to scheduling. Only then did Kristina Klebe get cast as Lynda
The Moody Blues' song "Nights in White Satin" that can be heard in the hospital scenes may refer to the vision Michael Myers has of his mother dressed in white on the night that he escapes from the coroner's truck.
The trivia items below may give away important plot points.
Despite this being Danielle Harris's fourth appearance in a Halloween movie, this is the first in which her character has died. However her previous character Jamie Lloyd was killed off after she was recast.
In the Unrated Director's Cut commentary Rob Zombie says that the original ending, the 3 main characters all die and Laurie Strodes psychiatric ward stay is really in fact her last thought as many mistake it as she's alive still.
(at around 1h 45 mins) In the director's cut, Michael takes off his mask and yells "Die" before stabbing Dr. Loomis. Based on this scene, it marks the first time ever in the series where the adult Michael Myers actually speaks. This is also the first time the character's face can be seen clearly.
Director's Cut Body count = 20 (plus the two people on screen and the one person off in the opening dream sequence); Theatrical cut = 19. In both cuts, two people are not killed by Michael Myers. There is also a pit of dead bodies that Laurie falls into in the opening sequence, but it is not verified that Michael killed them.
The original Halloween II (1981) took place entirely in a hospital. Although the 25 minute dream sequence at the beginning of the film where Laurie is running from Michael in a hospital is initially thought to be an intentional homage to said film Rob Zombie has since denied this especially because he has stated that he did not even like the original Halloween II.
This is the only Halloween movie where the character of Sam Loomis pretty much dies for certain. He may have been killed at the end of "Halloween 6: The Curse of Michael Myers," but that was never actually confirmed.
In the unrated directors cut Laurie is much quicker to anger due to her PTSD and gets into arguments with Annie and her psychiatrist. These moments were cut from the theatrical version, presumably to make Laurie more likeable. The unrated ending sees her turn completely psychotic and she is shot and killed by the police along with Michael Myers.