Corrected entry: When Rosalie Mullins walks down the corridor approaching Dewey's classroom there are children doing artwork as she walks past, she even comments on the child saying "three at once that is very clever". After she listens in at the classroom door she continues walking down the corridor as we can see her on the CCTV footage the children have set up. In this shot, however, the children are no longer painting where they were before and appear to be through the doors Rosalie is about to walk through.
Corrected entry: When The School of Rock goes back on stage for the encore during Battle of the Bands, the whole class goes on stage. If all the kids are on stage, who starts controlling the lights when they start playing the encore?
Corrected entry: How is it that Dewey can hear a light orchestra a floor below and a room across (assuming the bathrooms are in the same location on every floor, making Dewey not directly under the music room), but the class next door to Dewey's can't hear a yelling, guitar playing, drum-playing class through a wall (this was before the "roadies" soundproofed the room)?
Corrected entry: In the scene where the principal comes in and observes the class, Dewey improvises a "musical" math lesson, singing things like "9 x 9 = 81" and other very basic arithmetic lessons. But these kids are no younger than 5th grade, and at a fancy prep school they would already be way past those basic skills, but the principal doesn't even notice.
Corrected entry: The timing of the day of Battle of the Bands is very suspect. It has to be first thing in the morning, say 9:00 at the latest, because all the parents are in Principal Mullins' office demanding to know why she hadn't caught on to Dewey's fraud, and the new substitute for the kids hasn't arrived yet. Yet when they get to the performance venue, there's barely enough time for them to get ready and go on stage as the last band to perform. Allowing travel time and the time it took to pick up Dewey, it still can't be much past 10:00 AM. It's too hard to believe that a bunch of hard-rockers would be up that early to watch all those bands and that everything would essentially be over by that time.
Corrected entry: When Rosalie walks into the staff room to tell the teachers that it's parents' night, the camera shows her walking into the center of the room. In the face on shot, however, she is talking in the door way.
Corrected entry: How did the people who were running the Battle of the Bands know they were the school of rock? The girls made up the name after the audition.
Corrected entry: This isn't technically a mistake within the film, but it's interesting. The official title of the film is "School of Rock," yet in the opening credits, the title reads as "The School of Rock."
Corrected entry: During the scene when the Principal is coming to the class, the students hurry up and put everything away. When the kids are putting the drum set away they never put the high hat away. It just seemed to disappear.
Corrected entry: When "Fancy Pants" shows Jack, Freddy, and Kaity's new outfits, Jack hears Zack playing a song. He tells the band to come over and play it. Freddy and Kaity come over in their outfits, but when they start to get more into the song, they're now wearing their school uniforms.
Corrected entry: In the scene where the children are pretending to die from a rare blood disease, Freddy is lying on the ground. Then it skips back to Dewey talking to the talent director for the "Battle of the Bands." When Dewey is walking out of the building, he says "We're on the bill," but you see Freddy standing up jumping, how could he be standing up before he knew he was on the bill.
Corrected entry: Towards the end, when the band goes to play their second song on stage, it is made clear that everyone (the band and the crew) is on the stage. If that's so, then who's doing the lighting effects?
Corrected entry: As anyone who's ever played in a rock band would know, a room cannot be "sound-proofed" by taping padding around the edges of a door. The noise, especially the drums, would still be heard outside.
Corrected entry: In the scene where Dewey is at the bar with the principal, she takes a sip of her beer and Dewey gets up to pick a song. The shot then goes back to the principal to show her taking another "sip" but before she does, you can see that there is already less in the cup than when she put it down. (And I'd assume she hadn't taken another sip while the camera was on Dewey.)
Corrected entry: After the stylist kid displays his first designs for the band on the bass guitarist and the drummer, they go to play Zak's song. They start playing in their costumes, but in the next shot, they're in their school uniforms.