The BBFC loved the film and found the gore so comical and inoffensive that they seriously considered granting it a "15" certificate. In the end they determined that the sheer quantity of gore would confound expectations at "15" and therefore rated it "18".
The movie was finished under budget with NZ$45,000 remaining. Peter Jackson used it to spend two days shooting the park scene with Lionel and the baby Selwyn. He has gone on to say that it is his favorite scene.
Peter Jackson, is a well-known aficionado of the original 1933 version of King Kong (1933). In the beginning of Braindead, the New Zealand Zoo official is stealing the rat monkey from Skull Island. That's Jackson's nod to Skull Island's more famous resident, King Kong. Jackson would 'return' to Skull Island for his 2005 remake of King Kong (2005).
The tarot cards in the film are from Aleister Crowley's Thoth deck, but two cards, the Star and the Prince of Cups, are different from the ones featured in the deck, and they were probably specially prepared for the film.
Another connection to King Kong: Actor Forrest J. Ackerman (the guy who takes the picture of Lionel's mother crushing the rat monkey's head) is an uncredited "Fleeing Extra in Crowd" in the 1976 version of King Kong (1976).
Peter Jackson's character, the undertaker's assistant, is very similar to his character Derek from Bad Taste (1987). He has the same haircut and glasses, does the same, strange smile, and his character acts in a very similar way.