Continuity mistake: When Mr. Boy offers Layla a drink at the dance, the amount in the cup changes. Also, after Lash spills the drink on Mr. Boy, half the drink is still in the cup, but in the next shot the cups empty. (01:11:35)
Continuity mistake: The first time the bus takes off for Sky High, you see the name change from "School Bus" to "Sky High School Bus." In the next shot it says "School Bus" again. (00:08:50)
Continuity mistake: The school bus changes back and forth between a long and short version within several scenes.
Continuity mistake: When 'The Commander' gets mad in the kitchen, he hits the counter and all the utensils fly. Between shots the knives in the knife block change position and some disappear. (00:33:30)
Continuity mistake: In P.E., after Warren says, "Hey! Get your head in the game!", while Coach Boomer is giving them the rules to the game, the timer switches on, and the citizen gets lowered down. When the citizen starts out, its feet are pointing toward the timer board, but in the next shot, its body is parallel to it.
Continuity mistake: When Layla is being attacked by Penny she fights back using the plants, and breaks the window. As Penny is informing Layla that Royal Pain had broke the anti-gravity device the window is still broke, then the camera goes back to Penny and then again to Layla and to the right of Layla's head you can see the window fully intact again.
Continuity mistake: Kelly Preston's hair changes back and forth between shots, during the scene when the parents discover the party in their house, and in consecutive shots throughout the movie.
Continuity mistake: In P.E., when Will and Warren are up against Speed and Lash, the first time Will gets knocked over he gets thrown against a wall. When he lands on the floor, he is pretty close to the wall. In the next shot, after Zach says "Ouch", Will is much farther away from it.
Continuity mistake: When Will and Layla board the school bus near the beginning of the movie, Ron the driver chastises Will for asking if they are on the right bus and slams the door behind them. A few minutes later, when the Ron announces they are off for Sky Camp, he is shown pulling the "door close" handle again.
Answer: Will took Gwen to the Secret Sanctum. Later it's revealed that Gwen is really Royal Pain and since she saw the location of the Secret Sanctum, she would have told Speed, not Lash, as his super speed would be able to get him in and out without setting off the alarm. If Lash had tried to get into the Sanctum, he would have been caught.
He entered while Gwen was still visiting for the first time before she left.