When Character Replacements enter the story, they generally kidnap the Character they're replacing and stashing them into a plot hole. I think the plot hole i this story that the real London might be hiding is when Cody is in hospital, and Zack is asleep in the room next to him. Hospitals rarely, if ever, have adjoining rooms, and family or friends have to go home to sleep, no matter what, unless they're in a chair. If she got lost in that plot hole, chances are she's thinking she simply took a wrong turn from Shoe Planet.