Deliberate mistake: "The Creature's Revenge" (Adventure 3, Part 5): The 2-inch heels on Sapphire's bright blue boots disappear and reappear repeatedly. They're most often missing in the scenes she appears in with Steel, presumably so that her height won't exceed his. (00:15:15)
Deliberate mistake: Probably best for filming the scene, but Jennifer Hart pulls up and parks her car on the street on a red curb in front of an ambulance and walks away. (00:10:12)