Elvira's Macabre Mobile was created for the film. The 1958 T-Bird hard top was purchased for $2,500 and went through $7,000+ in alterations. The car has remained in the possession of Cassandra Peterson, who continues to use it when she does personal appearances as Elvira.
Elvira's (Cassandra Peterson) dress is cut in a specific way and her hair is long in the back to hide burn scars Peterson has on her neck and shoulders from an accident in her youth. Peterson has joked that her Elvira costume only shows "the good bits".
Cassandra Peterson's personal hand and body double for the film was Susan McNabb who was later assumed to be Cassandra's sister at hundreds of Elvira's public appearances. McNabb retired as Peterson's personal assistant in 2005 after nearly 20 years.
The Las Vegas scene was originally ommited from the shooting script because NBC executives thought it would be too expensive to build the set. So the film was shot and editied without it, and then screened for NBC executives to decide on whether or not to fund more money for the Vegas finish (which Cassandra really wanted). Ultimately, executives liked the film enough to fund the Las Vegas scene. The scene was shot a month later in a warehouse in the San Fernando Valley, but some parts of the song and dance were cut from the final film.
The comic book ripped up in the bowling ally is "The Amazing Spider-Man" #298 which ironically is one of the most valuable comics ever as it featured the first appearance of Spider-Man's arch nemesis Venom, and was the first Spider-Man comic ever illustrated by Todd McFarlane.
The issue also has nothing to do with "killing Spider-Man with plutonium" as stated.
The comic book that Billy reads is "The Amazing Spider-Man" #299 (Dated April 1988) titled, "Survival of the Hittist!" [sic] Written by David Michelinie and pencils and cover art by Todd McFarlane. At no point in the comic does anyone try to kill Spider-Man with plutonium, the plot actually involves Spider-Man tracking down a secret arms shipment.
Then-unknown Brad Pitt auditioned for one of the teenage boy roles, but Cassandra Peterson thought he was too cute and felt that Elvira wouldn't be interested in Bob if Pitt was one of the teenagers trying to get her. On her casting notes of his audition, she wrote next to his name, "Yum Yum!"
The tar that Elvira is covered in at the end of the Flashdance (1983) spoof sequence was actually black paint. Because of the time required to clean the paint off Cassandra Peterson and her costume, this segment was only shot once.