The trivia items below may give away important plot points.
The climactic scene was accomplished by using a nude man wearing a mask cast from Felissa Rose's face. There were talks, and even molds created for a strap-on prosthetic penis for Felissa herself to wear, but the idea was ultimately scrapped. The thin man who stood in for Angela in this one scene was a college student who needed to get drunk before he was able to do the scene.
Jonathan Tiersten was the stand-in and hand double for all of Angela's actions during the murders. This was done because he had more masculine hands with veins, which could better throw off the audience in regard to the killer's identity. He even donned a wig for the back-lit shot in which Angela finds Judy in the dark.