Patzer

The outside of the sorority house says Pi Kappa Sigma. A picture hung inside the house says Pi Beta Phi.

Before the phone call from Barb's mother, her shirt has three buttons undone. After the call, one button is undone. In the next scene, three buttons undone.

When Claude the cat first appears, during the first malicious phone call, his coat is short, Later, his coat is noticeably shaggier.

When Clare Harrison enters her room, her door is bare. Afterward, a bow appears on the same door.

Mrs. Mac is applying lipstick in the bathroom when she is interrupted. The swipe of lipstick on her upper right lip appears and disappears between shots after she steps out and drops the items in her purse.

The film is set in America, but several characters have noticeable Canadian accents. They could be Canadians studying in America. The sorority could the college's unofficial Canadian sorority.

Jess, an American college student, has a noticeable British accent. She could have been raised in Britain, developing an accent, before moving to North America with her parents.

When Barb uses her inhaler, she clearly doesn't push down as she breathes in the mist.

After Mrs. Mac was killed, a lot of blood should have been on the attic floor.

One time Jess answers the phone, it continues to ring for more than a second after she picks it up.

When Clare investigates the noise in the bedroom closet, her dialogue "Who is that? Who is it?" is looped and repeated.

When Billy first enters the attic through the window, his shadow reflected on the wall clearly shows the camera equipment he is carrying.

During the last tracking shot of the movie down the hall, the boom mic shadow is visible on the wall, and camera equipment is reflected in pictures.

When Clare enters the closet to check Claude, the camera points to Clare. A crew member and cord are moving in the background, to her right.

Five minutes in, when Billy climbs down the ladder, the shadow of a circular lens is on the wall, to the right of his hand. It happens again later in the film, when he comes down the ladder again.

Barb drinks a can of King Kan beer, which is only sold in Canada. The film is set in the USA.

Before the search party begins, a man wearing a Canadian beret is reflected in a car window when Mrs. Quaife is looking worried. The film is set in the USA.

About seven minutes into the film, when "the moaner" calls, the boom mic is clearly visible at the top of the frame as everyone gathers around the phone to listen.

The slide for the chain on the sorority house's back door is mounted vertically, not horizontally as it should be. Anyone could reach inside and slide it up to open it.