Continuity mistake: At the start, when the camera pans through the doorway of Ms. Darbus's classroom, Zeke sits on a tall stool that is about 3 feet high. Oddly enough, in the following shots, the munchkin stool he now sits on only reaches the height of about 1 foot. (Did they really think we wouldn't notice?) The wood stool also moves forward a few feet. (00:00:50)
Continuity mistake: During Ms. Darbus's class, as the clock ticks away, a backpack hangs on the back of Troy's chair in every shot, until it disappears when the bell rings and the students throw the papers. (00:01:00)
Continuity mistake: When Miss Darbus speaks before the bell rings, there are two lamps, a cushioned chair and a small table, with a skull and teacup atop it, beside her. When the bell rings they all disappear from the platform. But note that when Chad dances with Ms. Darbus, one of the 'vanished' lamp's reflection is visible on the giant clock. (00:01:20)
Continuity mistake: Before the school bell rings, Jason asks Ms. Darbus for her favorite summer memory. When everyone turns to look at him in the shot from the front of the class, there is a book under Troy's desk, which is not there in the previous or following shots. (00:01:25)
Continuity mistake: Just as they start to sing "What Time Is It" the top of Troy's boxers are visible above his belt. He starts out wearing light colored boxers, which change to dark, then light, and again to dark colored boxers during this song. (00:02:05)
Continuity mistake: In Ms. Darbus's classroom, when "school's out" is written on the board, the handwriting differs from shot to shot. (00:02:10)
Continuity mistake: As Gabriella and Troy dance out of Ms. Darbus's classroom, there are two books (yearbook and schoolbook) on Taylor's desk (in front of Jason). Next shot, when Ms. Darbus slams schoolbooks onto Jason's desk, there is only one book on Taylor's desk. (00:02:40)
Continuity mistake: During the "What Time Is It" dance routine in the cafeteria, in two close-ups of Gabriella and Troy, a couple of Gabriella's middle buttons are open on her white blouse, but are buttoned up in the wideshots. (00:04:45)
Continuity mistake: In Troy's kitchen, when he's on the cell with Fulton, in the front shot Zeke puts down a half eaten apple and holds a carrot in his right hand with an empty left. In the side shot, he holds an apple in his right hand and a water bottle in his left, but next front shot it's the same as the first shot. (00:10:00)
Continuity mistake: At Lava Springs, when Fulton hands Sharpay the marker (to autograph the talent show fliers) it is capless, but in the close-up as she signs her initials the pink cap is on the marker, but then it vanishes again. (00:11:35)
Continuity mistake: After arriving at Lava Springs, Sharpay places her sunglasses down on the desktop upside down facing away from her, but in the close-up the sunglasses are rightside up and are turned around. (00:11:40)
Continuity mistake: Having just arrived at Lava Springs, when Sharpay is about to initialize the first flier, Ryan takes another with his left hand as he holds the sunglasses in his right hand. In the close-up, as Sharpay signs her initials Ryan hands her another flier with his right hand, but in the third shot, Ryan still holds his sunglasses in his right hand as he hands his sister a flier with his left hand again. (00:11:40)
Continuity mistake: Having just arrived at Lava Springs, Fulton hands Sharpay the first of the talent show fliers for her to autograph, but in the close-up as she initials it there is more than one under her hand. (00:11:40)
Visible crew/equipment: After arriving at Lava Springs, when Sharpay signs her initials on the last two fliers in the wideshot, the reflection of the camera and crewmember are reflected on the surface of the Star Dazzle trophy, right beside Ryan's (blue shirt) reflection on its right. (00:11:45)
Continuity mistake: When Sharpay, Ryan and the three Sharpettes sit on their chaise lounges before "Fabulous" there are three large umbrellas behind them and a table with Sharpay's imported ice tea on it. It all disappears during the song; additionally, their large brightly colored bags and magazines move as well. (00:13:40)
Deliberate mistake: After Sharpay falls into the pool, when Gabriella dives in it is an obvious stunt double for the actress. (00:16:40)
Continuity mistake: In the Lava Springs kitchen, Kelsi holds up a dish towel, when they sing, "Maybe there's a better way to fix this greasy mess," and she drops the towel. The towel repeatedly moves around from the cart's bottom shelf, to the floor and disappears repeatedly throughout the scene. (00:22:25)
Continuity mistake: After Fulton gives the group their staff assignments in the kitchen, during "Work This Out" there are table order tickets hanging over the grill and fry stations. In some consecutive shots the amount goes from three to one, to three, to one, back to three, etc. (00:22:50)
Continuity mistake: During 'Work It Out', when Troy taps on the pans with the spoon the blonde Wildcat cheerleader walks behind him, in front of the stove. Just as another Wildcat (played by Charles Klapow, the choreographer) dances across the screen with a broom, the entire back of the kitchen is in view and she is gone. Then when it cuts to the close-up, the blonde Wildcat is back by the stove. (00:23:00)
Continuity mistake: During 'Work It Out', Gabriella grabs the large gold cookie tray from the side rolling cart and turns with it (couple of shots after she clinks the glasses), but next shot she grabs that gold tray from the bottom shelf of the large prep cart. What's particularly funny about that second shot is the fact that the gold tray was never on that prep cart's bottom shelf until later on in the scene, after Troy taps on it. (00:23:10)
Answer: It's a Musical. Instruments that aren't shown are always playing like this in these types of movies.