Goofs

In the trick-or-treat scene at the nursing home, Misty (Christina Ricci, who was pregnant during filming) has a noticeably larger belly than in her other scenes.

A central plot point is that the girls' periods have all arrived simultaneously. The idea that women's periods will sync up if they live together is a myth. Given the pacing of a menstrual cycle any group of women living together will always have some who are having their period at the same time just by the law averages.

In 1992 the girls are in the woods dancing to Michael Jordan's "This Is How We Do It" but that song was not released until 1995.

Kevyn calls Nat to tell her the results of Travis' post-mortem toxicology report. These reports generally take 8-12 weeks after a person's death to be completed and finalized, even for police use, so Kevyn would not have this information yet.

When they hear the noise from the attic, one of the girls says "the fuck was that?" The habit of dropping the word "what" from the expression "what the fuck" developed in the 21st century. No one in the 1990s would have spoken like that.

At Taissa's press conference a camera is making a film auto advance sound effect. It is doubtful a press person would be using a film camera.

When Jackie notices that Shauna isn't menstruating she jokingly suggests that Shauna must be pregnant. There are several reasons, aside from pregnancy, that a woman's period might be late, including both stress and malnutrition, which all the girls would be suffering from.