We first see Janet, the woman who would become the fourth victim, leaving her house and meeting Dottie while wearing a red and white striped dress. Later that evening when Janet calls the radio show, she is wearing a gray and white top. However, when her body is found the next morning, she is again in her red and white striped dress.
The psycho fires 15 rounds without reloading from a single-stack magazine model 1911 style pistol that has a magazine capacity of 7 rounds plus one in the chamber for a maximum total of 8 rounds. Later variants of the gun held more ammunition via a double-stack magazine, but they were not in mass production at the time of the series.
The Porsche 928 goes off the roof of the parking garage and rolls freely on its wheels after it crashes. The car clearly had no engine or transmission in it since it was in gear when it went over the edge.
After the psycho has fired his 15 rounds, the slide on the gun locks back, indicating an empty gun. He keeps pulling the trigger and a clicking sound is heard. On that type of gun, once the slide is back pulling the trigger does nothing, so no clicking sound could be made. This was an added sound effect.
The radio show is call-in only, yet the host has a mailing list to include home addresses. Since callers to a program such as that value anonymity, none would use their real name much less give their real address. Later the host encourages callers to not share this information as they may be in danger.