Will Brennan: Who hasn't? Michael Myers. It's like 20 years ago?
Will: And the girl that...what happened to the sister, she died, right?
Laurie: No, she faked her death... and now, she's the headmistress of a very posh, secluded private school in Northern California — hoping and praying every year...that her brother won't find her.
Ignoring the continuity of the last three films of the Halloween franchise, Halloween H20: Twenty Years Later picks up the story of Final Girl Laurie Strode (Jamie Lee Curtis). After faking her death to live in peace following the horrific events during the Halloween night of 1978, Laurie had changed her name to Keri Tate, had a son, and became a headmistress for a high school far away from Haddonfield, Illinois.
Michael Myers, however, has finally tracked Laurie down, and after two decades of waiting, he comes back into her life — and enters the lives of a number of students, including Laurie's son — in order to kill her once and for all...
While it offered a solid conclusion to the story of Laurie Strode, that didn't stop the suits from making a sequel.
Halloween H20: Twenty Years Later contains examples of the following tropes:
- Action Girl: Laurie has had enough of Michael's bullshit.
- Action Survivor: John, Molly and Ronnie who each try to fight off Michael and end up surviving.
- Accidental Murder: Will who is in a panic about Michael, shoots someone wearing a hoody he presumes to be Micahel when in fact it is Ronald. He is pretty shaken up about it.
- Actor Allusion: The character played by Janet Leigh gets in a car that is similar to one she drove in Psycho, with a piece of film's score playing in the background. She also tells Laurie that the shower is clogged - a reference to her character's famous death in the film. The character was originally intended as an Actor Allusion to PJ Soles - as it was named after her character from Carrie (1976), but it was played by Leigh after Soles failed to give them an answer, meaning that its name being similar to Psycho's antagonist Norman Bates was a coincidence. Likewise, Norma's motherly attitude towards Laurie was intended as this, to serve as a nod to the fact that mother and daughter were starring alongside each other.
- Advertised Extra: Joseph Gordon-Levitt, whose character died in the opening scene.
- The Alcoholic: Laurie has become this, though she's still functional. It's underlined by the lunch scene where she orders another wine while there's a full glass on the table already.
- And Starring: There is "introducing Josh Hartnett". He has done quite well for himself ever since.
- Arc Number: This film reveals the number seventeen to be this to the series. Michael murdered Judith and tried to kill Laurie when they were both seventeen, and John is now seventeen.
- Artistic License Geography: Michael drives from Haddonfield, Illinois to Northern California within 1-2 days. Even if he'd driven nonstop—which he didn't, he had to stop because his car broke down and steal another—that's impossible.
- Back for the Dead: Marion Chambers, who featured as a minor character in the first movie and played a bigger role in the second, returns in the prologue. Michael breaks into her house looking for details on Laurie. Naturally she doesn't survive the encounter.
- Balls of Steel: Michael takes a knee to the groin, but barely reacts.
- Big Eater: Sarah. While preparing a massive amount of junk food for a Halloween party, she mentions she's got such an intense love of food that it's actually a goal of hers to get fat. Charlie agrees with her philosophy.
- Black Dude Dies First: Inverted. Ronnie the security guard is mistakenly shot by Will, but appears at the end having survived.
- Bloody Handprint: Laurie leaves a bloody handprint on the door of a closet, tricking Michael Myers into thinking she was hiding inside.
- Brick Joke: A minor gag early in the film is Ronnie reading cheesy romance stories he's written to his wife over the phone. In the climax, when he's survived, he can be seen on the phone to her excitedly saying he's going to write a thriller.
- Buxom Is Better: Ronnie is narrating a story to his wife, and we hear him talking about a woman with "round, melon breasts".
- Michael lifting Will up with his knife after stabbing him is reminiscent of the infamous scalpel scene from Halloween II (1981).
- Molly spotting Michael lurking across the street from her classroom, precisely as Laurie did in the first film—and both during an English class, no less.
- The numerous Stealth Hi/Bye Michael pulls are also straight out of the first film.
- The song "Mister Sandman" is played over the film's opening, like it was over the beginning and end of the second film.
- Laurie gets stabbed through her sleeve in the same way she did in the original.
- Molly has trouble with her keys while being chased, just as Laurie was in the first film.
- Laurie tells John and Molly to go down to the street to get help from someone, just as she did for Tommy and Lindsey in the first film.
- Camping a Crapper: Averted. A woman and her daughter go to a public bathroom and Michael Myers follows them in. After a tense scene in which the audience assumes he is going to kill them, he ends up stealing the woman's car keys instead.
- Canon Discontinuity: Played with. The Jamie Lloyd portions of the franchise aren't mentioned (though they would have been in the original treatment) but it's hinted that they did happen - the photo montage at the start shows a bloody pair of scissors, as a nod to the fourth film.
- Car Fu: Laurie hijacks an ambulance van with Michael in it, and runs it off a cliff in order to kill Michael once and for all.
- Caught in a Snare: Laurie has a snare trap set for Michael.
- Celebrity Paradox: One of the college students watches Scream 2. Even though the first Scream showed Halloween being played.
- Character Development: Laurie Strode, who goes from a Damsel in Distress to a badass Action Girl in this movie! She even provides the page image!
- Cut Phonelines: At Laurie's school when Michael finds her.
- Dangerous Key Fumble: Molly does this as Michael closes in.
- Death by Sex: Downplayed. Charlie and Sarah joke about having sex and get killed - more than Molly and John who survive. Will is also more keen to do it with Laurie than she is, and he gets killed.
- Department of Redundancy Department: The subtitle, considering on how H20 already means that it has been twenty years from the first film's events.
- Disappeared Dad: John's estranged dad is an "abusive chain smoking methadone addict."
- Evil Overlooker: The poster had Michael Myers' Black Eyes of Evil looming over the frightened-looking protagonists.
"I think that Victor should have confronted the monster sooner. He's completely responsible for Elizabeth's death. He was so paralyzed by fear that he never did anything. It took death for the guy to get a clue." She goes on to say that Victor finally confronts the monster because he "had reached a point in his life where he had nothing left to lose. I mean, the monster saw to that by killing off everybody that he loved. It was about redemption. It was his fate."
- Laurie is teaching an English literature class on Mary Shelley's novel Frankenstein. Molly, one of the students, responds to a question about the book and fate with this:
- This foreshadows the final scenes in the movie where Laurie finally decides to stop running from Michael Myers and confront her monster. After twenty years of living in fear and seeing her loved ones murdered, she had nothing more to lose. It was time to face her fears and end the nightmare.
- Groin Attack: Laurie knees Michael in the groin. It doesn't do anything except cause him to give her a nasty glare.
- The Hunter Becomes the Hunted: At the end Laurie turns the tables on Michael Myers and starts hunting him down with an axe.
- Improbable Infant Survival: We're given a Bait-and-Switch thinking Michael will murder a mother and her young daughter, but he just steals their car keys. No victims are younger than a teenager.
- Irony: Laurie initially refuses to let John go on the Yosemite camping trip but relents and gives him a permission slip at the last minute. He decides to stay at the school for a party - and gets attacked by Michael Myers.
- Mama Bear: In the original movie, Laurie had no qualms attacking Michael in self defense. In H20, she really lets him have it when he attacks her son.
- Nonchalant Dodge: Michael's response to Laurie's knife throwing act.
- Off with His Head!: Laurie beheads Michael in the end. The next film changed this greatly.
- Oddball in the Series: Alternate continuity or not, this is the first—and only—film in the series to not take place in Haddonfield (the prologue notwithstanding). It also takes place over several days, whereas the other films took place over one.
- Oddly Named Sequel 2: Electric Boogaloo: No, the movie is not named after the chemical formula for water (H20 = Halloween 20 Years Later). Although, water has a PH of 7.0. And this is the seventh movie in the Halloween franchise.
- Oh, Crap!: From the audience's view. Michael tries to stab John and Molly through a closed gate with no success. Then he notices the keys on the ground, he picks them up and tries to normally open the gate. This shows that Michael may be a psychotic murderer but he's far from being brainless.
- Precision F-Strike: After Laurie catches John off campus, she says "what the fuck do you think you're doing?" - which even he is uncomfortable with.
- Prolonged Prologue: The prologue goes for almost 20 minutes before the opening credits begin.
- Recut: There's a TV Cut that trims the violence and cuss words, but also has some alternate scenes. One added scene gives the counselor played by Adam Arkin some development by revealing that his mother cheated on his traveling salesman father, and he got blamed for knowing, but doing nothing.
- Sassy Black Woman: Ronnie's wife. She manages to be this trope, despite never appearing on screen; only featuring on the phone.
- Say My Name: Laurie after she starts hunting Michael:"MICHAAAAEEELLL! MICHAEL!"
- Series Continuity Error: Michael has no burn scars, which he would have incurred from the second film (which is on this movie's continuity).note
- Series Fauxnale: Was written and intended to be the final chapter in Michael and Laurie's story and the ultimate end to the Halloween saga. Executive Meddling and the later sequel had different ideas.
- One character is named Norma Watson after P.J. Soles' role in the first film adaptation of Carrie. Soles also played Lynda in the original Halloween.
- There is also a cameo by Janet Leigh, mother of Jamie Lee Curtis and star of Psycho, which is the Spiritual Ancestor to the original Halloween. Janet Leigh drives the car she drove in Psycho, and her scene is scored with the music from that film.
- One of the teens who Nurse Loomis encounters is wearing a hockey mask.
- Laurie says "drive down to the Beckers", referencing Casey Becker from Scream (1996) - whose parents referenced Laurie's line from Halloween "drive down to the McKenzies."
- Slashers Prefer Blondes: Inverted. The lone blonde in the group is one of the few survivors.
- Stalker Shrine: It is revealed that Dr. Loomis' office is a shrine to Michael Myers, with three decades worth of newspaper clippings about Myers taped all over the office walls. To add to the creepiness, he also has high school photos of Laurie (Michael's sister) stuck to the wall too.
- Sudden Sequel Death Syndrome: Marion Whittington and Doctor Loomis. Actor Donald Pleasence passed away in 1995. At least his death was off-screen unlike Marion unfortunately.
- Throwing Your Sword Always Works: Averted. During the final confrontation with Michael Myers, Laurie throws several large kitchen knives at him. They all miss.
- Took a Level in Badass: Laurie has had enough of being stalked by Michael and takes the fight to him.
- Triumphant Reprise: A more triumphant sounding version of the theme plays as Laurie decides to track Michael down.