Russell T. Davies filmed the footage of Trisha Goodard and Richard and Judy.

There was a sub-plot (featured in the DVD) that featured Pete being seduced by a demon, played by Jo Joyner.

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.

Originally Steve's mother was a character, but after the scenes were cut, a line was dubbed in that she committed suicide years earlier.