The original “Freddy Snake” unintentionally came out looking too phallic. The crew only had one hour to film the scene, so they didn’t have enough time to paint it. So, it was covered in a green goo substance to overcome the “pinkish hue.” The scene involving the “Freddy Snake” attempting to swallow Kristen was also filmed backwards and then played in reverse, due to the gums on the puppet being too flexible, and were folding over themselves.
From IMDb Trivia: A Nightmare on Elm Street 3: Dream Warriors
The Devil's Muse 