There was a sub-plot (featured in the DVD) that featured Pete being seduced by a demon, played by Jo Joyner.
Russell T. Davies filmed the footage of Trisha Goodard and Richard and Judy.
The directions that Judith (Lesley Sharp) finds on the street, having been earlier dropped by a possessed woman asking her for directions, lead her to a laboratory. The room number, R153, is the word 'rise', obviously connecting to the subject of the serial.
The scenes set in the former manchester city stadium on maine road were actually shot shortly before its closure & demolition. The ground is now a housing estate.
Originally Steve's mother was a character, but after the scenes were cut, a line was dubbed in that she committed suicide years earlier.