According to John Carr himself, at first this movie was not finished. Then, some portions of the filmed materials were incorporated in the "Night Train to Terror" anthology. After that, Carr left USA for England for a time. When he came back to the USA he was amazed to find that the producers made a "complete" version of his movie, using almost all the materials filmed. This version was released on VHS as "Scream Your Head Off". Later, John Carr decided to finish his movie and shot new sequences with John Philip Law (noticeably older) and incorporated Marilyn Monroe (played by Francine York) in the story. This last (?) version is the one known as "Marilyn Alive and Behind Bars", "completed" in 1992. In résumé, there are THREE versions of this movie: - 1) one as a segment of "Night Train to Terror" - 2) the illegitimate version, "Scream Your Head Off" (in VHS only) - 3) Marilyn Alive and Behind Bars. Apparently, during the first shooting some scenes were filmed twice, with girls more or less clothed. The nude version of these scenes was shown in "Night Train to Terror". It also seems that some shots in "Night Train to Terror" were gorier than the "Marilyn" version. But it COULD have been specially filmed material by the producers of "Night Train to Terror", as it was made for the two other movies "cannibalized": "Cataclysm", and "Death Wish Club". Special sequences involving SPFX were filmed when abridged versions of these two movies were included in "Night Train to Terror".