The plot was virtually the same as that 'High School Musical', but with more similarities to 'Grease'.The character who would become Sharpay was to be the daughter of Betty Rizzo (producers tried to get Christina Aguilera for the part, but she declined).Bleu has said "The question isn't if we're going to do one, the question is when we're going to do one." "High School Musical" was just the working title for the film while a better name was thought up.
She auditioned several times and had a screen test, and was cast as Gabriella.
However, the fifth season of her TV show Degrassi: The Next Generation (2001) seriously conflicted with the filming of this movie, so Steele had to drop out.
In Corbin Bleu's first appearance at the school, he was wearing three different watches.
He was given a choice of which one he wanted to wear, so he chose all three of them. According to Corbin Bleu, whenever the principal cast members get together, they always discuss doing a High School Musical reunion.
At the second callback, Grabeel and Tisdale auditioned together and their Sharpay-Ryan dynamic was quickly established.
Grabeel claimed that Tisdale, in a Sharpay-like manner, gave him unsolicited direction in the audition.The reason for this is because Efron's natural voice was too low for that of a tenor and the producers wanted a tenor to match the role.Efron did, however, do all of his own singing in the sequels, as all the music in those films had been tailored specifically for his voice.Zac Efron's singing voice was that of Drew Seeley, who tested for the role of Troy.Seeley sang the entirety of "Get'cha Head in the Game" and the reprise of "What I've Been Looking For." Efron only sings the first four lines of "Start of Something New," the first sentence of "Breaking Free," and during the scene on the balcony.The final callback for Taylor came down to Coleman and two Asian-American actresses.