Continuity mistake: Erin's dorm room door is not consistently the same. The door knob is initially unusually low, but higher thereafter. The posters and decorations are probably less than one foot higher than the door knob, but are higher later. At times, the posters and decorations should be within the camera's range but cannot be seen. Sometimes, Erin's head is almost to the blue along the top of the calendar, but is a few inches lower other times. (00:18:40 - 00:19:45)
Continuity mistake: At the "Wave Hair Salon", Ms. Gordon has a curler/roller at the top of her forehead. In some shots, it is straight, but in other shots it is angled. A little later, Christine goes over to Ms. Gordon and starts rolling down the curler to the top of her forehead as if for the first time. (00:08:04 - 00:08:47)
Factual error: During one scene, a police siren can be heard in the background. However, this was 1960/1 and police sirens were not introduced into the UK until 1963. Before that, police cars had bells.
Continuity mistake: The sizes, locations, and smoothness of the pieces of glass remaining in the wall mirror after Aidan smashes it with a bat change. Initially, there were a few large and several smaller jagged-edged pieces around the top and upper-half of the right side. Later, there were four relatively large smooth-edged pieces spaced around the upper half of the mirror - one in each upper corner and one on each side at the middle. (00:15:48 - 00:19:33)
Continuity mistake: There are some continuity problems during the cafeteria scene where Fern is being introduced to her co-workers. Fern is holding a banana, peeled almost to the bottom, and has several slices of banana on her peanut butter sandwich. There is another banana peel on her paper lunch bag. Fern is shown taking a bite of her sandwich. A little later, Fern is holding a partially peeled banana but no slices can be seen on her sandwich. If this is her second sandwich, she already peeled two bananas. (00:05:59 - 00:06:32)
Factual error: The movie is set in the 80s (you can see tell for instance by the driving license of the old woman, which uses the 80s template and has a 1985 date), but the police plays the suicide tape on a Panasonic PV-4614, which is a late 90s model of VHR. Same goes for the Sony video camera used to tape the murder, definitely from the 90s. (00:19:00)