Revealing mistake: At the scene where all the spy kids are fighting the waiters, watch Gary as he is fighting. The waiter he is fighting throws him back, but then Gary activates his rockets shoes. Yet to activate those shoes you have to tap them together. The rocket shoes activate a few seconds before Gary tapped his heels together.
Revealing mistake: As Juni runs to save his sister from the skeletons, he fights two of them (one wearing a helmet) before running out to the rocks that she is standing on. After he defeats the skeletons and runs off screen and immediately before the scene is cut to show the outcropping with the kids on it, there is one frame where the skeleton disappears from the shot immediately before the cut.