When Ray is posing as the Great Stantzo, his fake mustache keeps disappearing and reappearing between shots.
When the Ghostbusters go to the Magic Palace, Ectomobile's license plate incorrectly says "ECT-1"
After Ray disappears inside the cabinet, Winston, who is standing outside the cabinet, is colored like Ray.
After Winston says "All right, "New York City!", he puts his arms down and the lines of his body and that of Peter's are visible through his hands.
The moment Peter adds a fake mustache to Ray's face, Ray's hair turns white. A moment later his jumpsuit is now colored to look like a green shirt with blue pants. At the end of the sequence, his hair and jumpsuit change back to their normal colors while he is still wearing his magician's hat and cloak.