Goofs

Veronica's hairstyle constantly changes, often between shots (bangs/no bangs).

Veronica picks up the cup of poison covered by its lid, but then in close-up she is carrying the relatively harmless uncovered cup, which a moment later is back on the counter for J.D. to look at.

When Heather C is setting up her backswing with the croquet mallet, the positioning of Heather M behind her alternates between close and far back, depending on whether the shot shows their feet or upper bodies.

Early in the movie, during the frat party, Veronica throws her burning glass out the window and it lands in a trash bin that sets on fire. When she leaves the house, the fiery trash bin is not under a window.

When Veronica fights in the school hallway with Heather Duke about the petition and then with J.D. about getting back together, she has a flower accessory where her shirt buttons. When she returns home the flower is gone.

Kurt and Ram take Heather and Veronica cow tipping. Cow tipping is not real; it is an urban legend that originated in the 1970s. It is not physically possible for two people to push over a cow.

In the cafeteria scene it's impossible for extras to pass behind or walk by J.D. since he is sitting in a corner by the windows.

Moby Dick does not contain the word "Eskimo" in that spelling, but does contain "Esquimaux" which is the French Canadian spelling.

When Veronica and JD are waking up in the school parking lot, Veronica holds her left arm carefully. When she takes the lighter and puts it on the palm of her left hand, it is obvious that this is not a real hand.

When Martha Dumptruck is alone in the gym drinking her soda through a straw, we see through the bottom that she finishes it all. She then spills the finished soda on the front of her shirt.

When Veronica comes out of the Snappy Snack Shack with the large Slushee that JD just bought for her, she waves it around and holds it with a bent wrist in a way she couldn't possibly do if it were almost full of a heavy liquid (revealing that the cup is actually empty).

Heather McNamara's hairstyle during the first scene is different than in the rest of the movie. This is because actress Lisanne Falk cut her hair short and had to wear a wig to be consistent in length with the rest of the movie's footage she appears in.

Westerburg High School's gymnasium's exterior and interior do not match with each other. Its interior has tall, arched windows that the exterior does not have. This is because the exterior for Westerburg High School's gym in real life during filming was for the auditorium of one school and that Westerburg High School's gym's interior on the other hand was filmed at another school in its actual gym.

In the DVD extras Winona Ryder's bio states that her film Little Women was directed by Gillian Anderson. It was actually directed by Gillian Armstrong.

Heather Chandler drinks poison from a coffee cup that is clearly empty. This was so that actress Kim Walker would neither die nor be hospitalized at the time of filming so she wouldn't actually drink anything poisonous or harmful.

Despite the movie's setting taking place in the fictional town of Sherwood, Ohio, the movie's scenes were filmed in California, which is way out of place for the setting taking place in the easternmost state in the Midwest.

Just after JD and Veronica murder Heather, she observes that she is going to have to send her SAT scores to San Quentin instead of Stanford. Now, even if she was intending to go to Stanford University, which is indeed in California, not far from San Quentin State Prison, the killing occurred in Ohio, so she would have to go to prison - or death row - in one of their state prisons, most likely then at the Southern Ohio Correctional Facility Lucasville.