Banned in the UK until 1999.
Could have easily escaped the UK's "video nasty" list if the original pre-VRA video cover wasn't so graphic. it featured a very bloody close-up of a drill boring into a man's head with lots of blood. The video cover was featured in video catalogs and received many complaints.
In 2017 just before the re-mastered film was to be re-released on DVD/Blu-Ray, an alternative pre-release version was discovered. Arrow Films (UK) was given permission to release this 100-minute version alongside the 96-minute theatre version. The new footage includes extended versions of scenes already in the theatrical version plus a couple of entirely new ones pre-cut before release.
Abel Ferrara claims that half of this movie was shot in 1978 and the other half was shot in 1979. This explains why the actors' hairstyles and looks in general change quite frequently during the movie.
While Reno is painting Tony's portrait, Tony is reading to him from the "Dictionnaire Infernal", a book that describes demons and their hierarchy in hell. The passage refers to Ronove/Ronwe, a demon who teaches "art".