When ditching Chad for the auditions, Troy is wearing gray boxers (as seen while running down the stairs). But later (same day) at the auditions, he is wearing white boxers (as seen when he comes out from behind the wall and raises his hand to sing with Gabriella).
In "Breaking Free" when Gabriella gets nervous and doesn't sing, the skyline doesn't come down and the lights stay on, as if the stage crew knew she wasn't going to start singing the first time. When Troy talks to her and gets her to sing, the skyline comes down and the lights go out.
At the end of the movie before the song "We're All In This Together", Chad starts the "Wild Cats" chant. Whenever he says "What Team", a voice can be heard behind him. This is the result of an off-sync voiceover.
In "Stick to the Status Quo," all the jocks are singing to Zeke about baking. When they all point to the basketball at the beginning of their part in the song, if you look in the background directly behind Zeke, Jason points too early and pulls back, knowing he timed the dance move wrong.
When Gabriella and Troy are running around the set (specifically the moon) as they are about to finish singing "Breaking Free", a glimpse of Ryan bobbing his head to the beat is seen. Ryan and Sharpay are supposed to be annoyed because Ms. Darbus allowed Gabriella and Troy to continue with their callback audition.
Kelsi is forced to start playing the music for "Breaking Free" from the start because Gabriella is too nervous to sing the first line. However, each time the song is practiced before this/played for the second time in the actual musical, the first line is actually sung by Troy.
After being in class and Troy is waiting for Gabriella outside the classroom, The class is walking out of the room. First we see Jason (blue shirt and yellow t-shirt) walk out. Then when Gabriella appears, we see him walk out again.
When Troy is running away to get to the musical audition, he starts off by wearing black three stripe tennis shoes. Then when he is running outside, he is wearing white tennis shoes. And then, when he is back inside, he is back to wearing the black tennis shoes.
When Gabriella is watching Troy on the laptop, she is crying when she looks out the window. When she turns around and starts singing "When There Was Me and You", her face is dry and we didn't see her wipe it at all.
When the girl sings about hip-hop being her passion during "Stick to the Status Quo", in the close-ups of her table, there is a milk carton beside her with a long straw sticking out of it. In the wide shots, the milk carton has no straw in it.
In "Breaking Free" there is a point where you can see part of Gabriella and her shoulder. It appears that she is wearing her pink shirt that she has on underneath her Decathlon uniform, but she hasn't taken it off yet.
Towards the end of "Stick to the Status Quo", Sharpay and Ryan begin walking down the stairs in a close up shot. In the following few wide shots, they are both still in their positions atop the cafeteria. This position switch happens many times.
When Troy tries to ditch Chad to go to the musical audition, he is wearing a belt (as seen when he is going down the school stairs). However, when he makes it to the audition he is no longer wearing a belt.
In the cafeteria scene, when Gabriella slips in the spilled milk, her tray is not only shot up, but tilted as well. However, after the camera cuts back to Gabriella, there is a cup of "sauce" yet it doesn't slide or tip off the tray.
In the homeroom scene, Ms. Darbus says "Mr. Bolton, I see that your phone was involved so I will see you in detention." and we see a close-up of Troy with both of his hands resting on his cell phone, with one hand ready to close the phone. The camera angle zooms out, and, instead, we see one hand resting on his lap and one hand holding the phone.
In the musical cafeteria scene, after Zeke confesses that he bakes, there is a brown paper bag (standing up), some food, a water bottle, and a basketball on the table. In the next shot, there is only a basketball and a water bottle. In the next shot, the lunch bag is back, but laying on its side. Later, there is a milk carton with the lunch, and during the middle of the song, there is nothing on the table at all.
When Troy's mom tells Troy to get ready for the "young adults party", his dad gives him the ball. After showing his mom's reaction, the camera turns back to Troy, but his dad is still holding the ball.
When Sharpay is printing off the article about Gabriella, the computer clearly shows she is printing an article with a picture on the left. However, the printer prints an article with a picture on the right.
During 'When There Was Me and You', Gabriella turns and starts to go down a flight of stairs, yet in the next immediate shot she turns and is walking along the corridor. Although throughout the clip the timings and positions change, as in many musical clips, they do at least follow on smoothly whereas this one changes drastically.
In 'We're All In This Together', after Gabriella does her solo part everyone is jumbled up, yet when the camera pans out they're all in perfect order, in what is supposed to be a directly continuous shot.
At the Scholastic Decathlon, Taylor sends an Internet signal to disrupt the electronics in the sports hall. After she has sent the signal we clearly see her close the laptop. When the film cuts back to her a few seconds later, just before the chemical starts smoking, we see her close the laptop again.
During "Stick to the Status Quo", Gabriella's food stains Sharpay's coat and under shirt. In the next scene Sharpay is in, she is picking out a new shirt and the coat is still stained; however, the undershirt is clean.
Right after the final basket is made, only the Wildcats and cheerleaders are on the court. In the next shot, when Coach Bolton brings out the trophy, he has to fight his way through a crowd of students, all of whom subsequently disappear when Troy is lifted up holding the trophy. The crowd is back when Troy is set on his feet.
In the lunch room scene, when Gabriella and Troy bump into each other, but are not speaking, we see Gabriella with a lunch tray in her hands. She sits at a table and puts the lunch tray down in front of her. The next time we see her (just a second later) the lunch tray is gone.
During the song "Stick to the Status Quo" Sharpay walks to the top of the stairs, going toward Gabriella. In one shot she starts walking, in the next she is in the background standing in her beginning position. The next shot is Sharpay half-way down the stairs.
When Sharpay walks over to the balcony, just before "Stick to the Status Quo" begins, as the camera pans over her, then down to the cafeteria, the camera is reflected in the glass screening of the balcony.
In the shot showing the front of the school where the buses are pulling up, all the cars have orange license plates on the front. In New Mexico, where the story was to have taken place, the license plates are yellow and they are only on the backs of cars, not the front.
When Troy and Gabriella go to the roof of the school he is in a t-shirt and there are flowers blooming. According to the story it is supposed to be the middle of January. Albuquerque is at an elevation of 5,280 ft above sea level. The temperature is in the low to mid 40s during the day and below freezing at night. There are no green or blooming plants. Also the grass is green in Gabriella's yard and the leaves are on the trees.
When Troy and Gabriella swap phone numbers after New Year's, Troy takes a photo of Gabriella by pointing the back of his phone and clicking. Troy's phone is a Nokia 6260, where the camera lens is located at the side of the phone.
When Troy and Gabriella swap cellphones to give each other
their number, they take a picture and put in a number. Both Troy and Gabriella put in less than six keystrokes, while the US standard for cellphone numbers is seven digits (probably 10 or 11 digits as the number is probably outside the local calling area).
After "Stick to the Status Quo", Ms. Darbus storms into Coach Bolton's office, which is located in the boy's locker room. In an actual high school, a woman would never be allowed into the male locker room, especially not a teacher.
Ryan and Kelsi are both known for wearing multiple hats. However, very few high schools in America allow students to wear hats during school hours. Wearing hats in class is strictly and widely prohibited.
During "Getcha Head in the Game", there is a player with the number 00 on the back. In a traditional basketball game, there is no such number used for a player. However, this scene is something of a fantasy, so this unrealistic element is allowed.
When Sharpay storms into the girls' bathroom to track down Gabriella, she walks past where Gabriella is hiding behind the wall. The camera also shows that there is no adjacent room behind that wall. When Sharpay turns to walk back out, there is no way that Gabriella could not have been seen by Sharpay as she would be in her line of vision.