The trivia and in jokes abound in this film. Firstly, you have Janet Leigh (Jamie Lee Curtis' mother) playing Norma (reference to Psycho) and complaining that the "showers are blocked again" (second reference to Psycho). In her last scene in the film, Janet Leigh is about to get into and drive away in the same car that she used in Psycho.

Not a mistake, just something to notice: When the guidance counselor is checking on Molly and Sarah, they are watching Scream 2, the scene where Cici (Sarah Michelle Gellar) gets killed. As he enters the room and says their names, watch the TV. As he says "Sarah", Sarah Michelle Gellar turns around.

In the first movie, Laurie sees Myers while she is looking through a window during school. The teacher surprises her by asking her a question and her answer is about fate. When she looks back out the window Myers is gone. In H20 Molly is looking out a window during school, she sees Myers, Laurie asks her a question and her answer is about fate. When she looks back out the window Myers is gone.

So the two girls are watching Scream 2 on the TV are they? Well, they specifically reference Halloween in Scream, so if the girls have seen Scream, they must surely know about Halloween, and how it was only a movie and they are in fact only movie characters and not real people. Hmm...

Late in the film, before Laurie/Keri goes back inside to battle Michael alone, she tells John and Molly to "drive down the street to the Becker's". This is a reference to "Scream," in which Casey Becker's father told her mother to go "down the street to the Makenzie's", a line included in the original Halloween.

Janet Leigh not only gets into the same make and model car as "Psycho" but it also has the same license plate number: NFB 418.

In Halloween H20, Laurie Strode changed her name to Miss Tate, this name also refers to Sidney's teacher in Scream, when the police are interrogating students. Check the Scream movie for the teacher's name.