When Tessa leaves school, she is wearing her knee socks. However, when she is attacked she is wearing nylons.
Each time the high powered lines are shown, there is an odd sizzling noise. High power lines do not make any sounds.
When Susan (a light haired girl) is being killed and "her" shirt is being ripped off, you can clearly see it's the same bra that Tessa was wearing when she was being raped. The girl that was being killed in that scene was a dark haired girl, making it clear that the same scene was used when Susan was killed and Tessa was raped.