Factual error: Sharp, distinct text and even graphics are shown projected from an early laptop screen onto the faces of Angelina Jolie and Jonny Lee Miller and even against a wall several feet in the background (starting 0:50:35 and throughout the rest of the movie). Of course, computer displays have never projected sharply-focused text or images onto user faces or any other nearby surfaces. (00:50:35)
Other mistake: Dade is standing with Phreak in the school hallway waiting for the sprinklers to go off. We know in the previous scene, Dade sets the sprinklers to go off at 9:30 am. After Dade opens his umbrella, the camera cuts to a close up of the sprinklers going off. The clock, above the doors of a classroom to the left, shows it's 10:30 am. (00:19:25)
Continuity mistake: After Dade and Kate go into the bet, Dade is seen writing notes and passwords on his notebook with a pencil. In the close-up, you can see everything he'd written down is in blue ink.
Plot hole: To play a practical joke on Dade Murphy and other new students, they are told, "There's a pool on the roof." The victims accordingly go there and are trapped by the roof access door being one-way until – we don't see how or who frees them (Janitor? The least-mean of the prankers?). How do the new guys get onto the roof in the first place? I should think that the aforementioned access door would be locked to prevent it.
Suggested correction: Compared to half the mischief they cause, picking a lock is easy. I, myself, learned how to jimmy my middle school's door locks with my student ID and accordingly let myself in, and even did so in the sight of other students. It's only because I lacked their level of will for mayhem, their imagination for excuses, and, more importantly, their level of powerful parents to perform legal rescue, that I stopped doing so before the teachers got suspicious.
Suggested correction: This is in the form of a question. You can assume they lock the roof door, but they don't have to. Or, the person tricking them has unlocked the door for the prank. Or, they picked the lock. Plenty of possibilities, I'd say.
