Character mistake: Chad actually steps on first base before the baseman has the ball. He was safe.
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: When Troy jumps into the pool, there is a huge colorful beach ball right beside Troy in the water, but in the next wideshot when Gabriella jumps in, the ball has vanished - and most of the pool is seen in this shot.
Continuity mistake: Before Vanessa Hudgens' stunt double is seen diving into the pool, you can see Vanessa already in the pool swimming towards Ashley Tisdale as she stumbles backwards into the water.
Audio problem: Near the end of the song 'Everyday' when everyone in the circle has moved forward to the centre of the stage, Troy turns back to the audience singing 'everyday' and you can hear Gabriella's voice but her mouth is not moving at all.
Continuity mistake: The shadows of the players during the baseball game change from shot to shot; sometimes they are behind the players and others they are in front of the players. Even though shadows change positions during the course of the day, this is too rapid and out of sequence for a normal afternoon.
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: In the scene when Troy and Gabriella kiss, when they are about to kiss for the second time, the wide shot shows Troy putting his hand on Gabriella's neck, but in the close-up she is seen putting her hand on his neck.
Continuity mistake: In the very first scene, before Jason asks Ms. Darbus about her past summers, the clock behind Ms. Darbus has the second hand close to the 9. However, after Jason asks his question, the second hand is back at the 7.
Continuity mistake: In the scene where Troy is playing basketball and Gabriella comes up to him, his jacket sleeves keep changing between being all the way down and being pushed up to his elbows.
Continuity mistake: In the scene where Troy and Gabriella are having a picnic on the golf course, the sky consistently changes from a blue sky to a cloudy sky to a sunset sky then back to a blue sky.
Continuity mistake: During the song "Fabulous," when Sharpay sings "Everything's got to be perfect, for me," she throws her arms down and they are fully covered by her robe, but in the closeup of her face her arms are completely bare.
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: During the scene when Troy is teaching Sharpay on how to golf after Troy leaves Sharpay puts one golf ball on the ground. The next shot on the close up of the golf ball you see that two other balls have shown up behind the club. Then when she hits the ball it's back to one.
Revealing mistake: After Ryan is given the Star Trophy at the talent show, the classmates gather outside holding lanterns. The line pulling Troy's lantern up is visible, just as the first blue fireworks starburst explodes above it. (01:44:10)
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: During 'Work It Out', a dark brown pepper mill is lying under the large prep cart which disappears and then reappears. (00:23:30)
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 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: At the piano, Kelsi clutches the sheet music titled "Troy and Gabriella's Song" facing out, but when Sharpay grabs it, in her close-up the title is not written on either side. (00:58:35)
Answer: It's a Musical. Instruments that aren't shown are always playing like this in these types of movies.