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: Both Jason and Chad, who are wearing blue shirts and white aprons, are serving burgers, when Troy tells Chad that he wants Swiss cheese on his burger. Next shot in the kitchen, when Chad hands that burger to Zeke to add the Swiss, behind him Jason has been on kitchen dish duty wearing the green tee and blue apron. He can't be in two places at once. (00:57:55)
Revealing mistake: When Troy crouches down on the rocks, and leans down to see his reflection in the water, oddly the reflection is not reversed, yet his hair is combed the opposite way. (Did the director actually think that if Troy's hair was combed the opposite way it would pass as a reversed reflection?) Additionally, when he crouches down, the bottom button on Troy's shirt is unbuttoned, but in the reflection (as well as in the previous and following shots) the bottom button is buttoned up.
Continuity mistake: During "Work This Out" in the close-up when Troy sings, "A way to have fun," his name tag disappears, then reappears.
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: At the U of A basketball court, in the overhead shot Troy sits down beside a crumpled white towel, which disappears in his close-up as he calls Gabriella's cell. That towel returns in the subsequent overhead shot, when he continues to play basketball. (01:08:40)
Continuity mistake: The binoculars in Ryan's right hand disappears and reappears after the sprinklers have been turned on, when he and Sharpay spy on Gabriella and Troy. (00:27:15)
Continuity mistake: After winning the Star Dazzle award, Ryan hugs Sharpay with the trophy in his hand. Part of the star at the top breaks off (watch Kelsi's face as it flies past her), as the rest of the star on the trophy bends down. In the next shot the star is intact. (01:43:05)
Visible crew/equipment: Throughout the film, set equipment such as the boom mic and pole, reflector screen or monitor are visible in the reflections of characters' eyeglasses and sunglasses. Such as when one of the Sharpettes asks, "So what's the theme of the summer's talent show?" in Sharpay's next close-up the boom mic and pole are visible in the reflection of her sunglasses.
Visible crew/equipment: During Fabulous in the beginning of the song if you look into Sharpay's sunglasses you can see a white light reflector.
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)
Trivia: Miley Cyrus has a brief cameo at the end of the film in the musical number "All For One". She is seen in a quick close-up, wearing a yellow top, dancing with other people on the rocks around the pool.
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.
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: At the start, when the camera pans through the doorway, as Ms. Darbus speaks on the 'stage', there is nothing between Zeke and the doorway. In the next shot, a tall wood stool appears out of nowhere right beside Zeke. Also, the height and structure of the stool he is sitting on changes.
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)
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: 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)
Answer: It's a Musical. Instruments that aren't shown are always playing like this in these types of movies.