Continuity mistake: Right after the cheer off, there's a wide shot of Kim and Ron. As Ron is saying, "Uh, yeah about that," he moves into a shadowed area (look at the lockers). It cuts to a close-up as he says his line, and he's still entering the shadowed area.
Continuity mistake: In the episode where the villain is in Smarty Mart (forgive me, I forgot the name of the episode), Wade has a cup beside him. Then he smashes the cup. The shot switches to Kim. The next shot of Wade, the cup is back to normal, and he takes a drink out of it.
Continuity mistake: When Drakken and Shego are watching Kim from a railing at the mall, the colors of Shego's top are switched. The right side of her top is black while the left side is green, her right sleeve is black, and her right glove is green, and her left sleeve is green, and her left glove is black, her right shoulder is green while her left one is black.
Naked Genius - S2-E1
Continuity mistake: After Ron writes the answer to the math problem on the board, writing appears and disappears below his answer between shots.
Answer: From technogenius Wade. There's at least one scene in the show where she gets some new gadgets from him.
Kathy Tjarks