Came to attention of the British censors as a video nasty in the early 1980s mainly because of several gimmicks, which included providing a vomit bag with the video and a competition to guess the weight of a 'brain' in a jar.
During the scene when George is in the booth with Tara Alexander you can see in the reflection of the glass that he is holding the telephone receiver to his left ear, but when the camera is on him he is holding the receiver to his right ear.
When the young man is smoking on the stair, he is only wearing his underpants, the scene then cuts to his girlfriend taking a shower, then we see him back on the stair, smoking, and then he is wearing a t-shirt too.
What are the differences between the R-Rated and Unrated Version?
The ordinary slasher movie about a sick twisted serial killer has been released in two versions in the US: an R-Rated Version censored in violence and plot plus an uncensored Unrated Version. In the UK, only the R-Rated Version is available. Furthermore a less censored version by World Of Video 2000 was released on VHS but that release was banned and put on the list of "Video Nasties". A detailed comparison between both versions with pictures can be found here.