How's Bernice (the Fake KC) able to travel between Zane's Barn Based Hideout and the Cooper's House that quickly?
It's never explained why Marissa got hold of KC's Laser Lip gloss, when captured with KC to prevent her from interfering with their plan upon learning having blown Bernice' (the Fake KC) cover after she had no idea that Marissa already knew that she and her family are spies.
At the End of Part 3, KC was tied up standing up whilst captured by Zane in his Barn Based Hideout, but in Part 4, she's hand cuffed to a post sitting on the Floor.
At the end of Part 3, Bernice had been Punished after arriving at the Cooper's House, with Craig and Kira believing that she's the Real KC, though in Part 4 she's no longer punished, being able to "go out dating" with Brett, be given cake, and go to a party with Marissa, as well as other stuff Zane mentioned to the Real KC in his Update from Bernice at the start of the episode.
Brett does not question Bernice wearing a different pair of clothes when the Real KC arrives to put a stop to his plot at the Organisation's Headquarters (since they wear a different set of clothes from each other in that scene).
How was Zane having Ernie and Judy held hostage at the Cooper's House able to communicate with Craig and Kira on a screen while at the Orgination's Headquarters?
Despite being imprisoned for two weeks, K.C.'s manicure is as polished and glossy as if freshly applied.