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: 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.
Continuity mistake: Troy's tan changes between scenes (and even between shots) throughout the movie. He starts off with no tan, then throughout the movie his tan changes in shade. In the final scene, "All For One," he is back to having little to no tan.
Continuity mistake: When Sharpay is practicing golf, the position of the golf balls changes between shots during the scene.
Continuity mistake: During the song 'Fabulous', by the swimming pool, Sharpay's shoes disappear, then reappear.
Continuity mistake: When Chad and Troy show up to caddy for the Evans family, the positions of Ryan and his mother, as well as the golf club bags, change depending on camera angle. The shadows they all cast also repeatedly change.
Continuity mistake: In the L.S. kitchen, when Fulton gives Troy the suit and tie, the hanger's metal swivel hook changes direction between the three shots.
Continuity mistake: During I don't dance after the dance with the bats and then Chad's group comes in they throw or do something to the bats the next shot they are gone and then you don't see the bats for some time and then after some time they come back BUT there are not enough bats for the team.
Continuity mistake: In the very beginning of "Go My Own Way," Gabriella starts to turn away from Troy twice; once in a shot from over Troy's shoulder and again when it is a side shot of the two of them.
Continuity mistake: During the final dance scene, "All For One," the sky in the background constantly changes from blue and cloudless to overcast.
Continuity mistake: During "Everyday" Troy's microphone keeps switching hands.
Continuity mistake: During "Work this Out" you see a girl pass by Taylor during the line "I don't remember you saying the boss is such a creep". The next shot you see the same girl move by closer to Taylor.
Continuity mistake: Troy's hair constantly changes throughout the movie.
Continuity mistake: During "What Time Is It" Jason is laying his head on his desk. His arms are change between shots.
Answer: It's a Musical. Instruments that aren't shown are always playing like this in these types of movies.