Continuity mistake: Velma places the robot engine below the locker's lock. In close-up the wires at the top of the mechanism stick out in a curve ending up on the same level of the lock's bottom, but in wider shots that follow they are instead folded down. Of course it's just a minute detail when you consider that in other shots the engine is instead at the SIDE of the lock. (00:35:30)
Continuity mistake: The scene with Daphne and Velma trying to talk some sense into Carol about the Spencer issue begins with Daphne close to the gap between two tables (look at the shot that precedes the moment when Velma clears her throat), and seemingly no space for anyone to join on Carol's left. When Mikayla joins she finds a lot of space though, and no wonder; from a wider angle it's obvious that now it's an entirely different table. (00:29:20)
Continuity mistake: Velma reluctantly agrees to Daphne's idea to check out of the mysterious locker. She says "We'll come up with something." Right part of the frame, and in the background there's an extra (black kid with a plaid white shirt) that is simultaneously also eating at the table in the reverse shot. (00:31:15)