Liam Aiken was originally set to play Will, and had just been accepted to NYU's film school. He was later replaced by Gaelan Connell who left NYU's film school mid-semester to take on the role of Will.
All of the instruments and singing in the movie were recorded by the actors, with the exception of the guitar parts of Vanessa Hudgens, Scott Porter, and piano parts of Lisa Chung. Although Hudgens and Porter learned how to play their songs, they were dubbed by guitarist Jason Mozersky.
All of the vocals for this film were filmed live by each of the cast members who sang, as mentioned by director Todd Graff. One of the requirements for the film was that all actors had to be able to provide their own vocals.
Because Aly Michalka (Charlotte Barnes) was on tour with her sister AJ Michalka (Aly & AJ) and Miley Cyrus, she didn't arrive in Austin until midway through rehearsals. Conveniently, the tour's last stop was in Austin, Texas, where rehearsal and filming for the movie took place.
The movie was released to great critical acclaim, but only took in $2.7m in the first week. The press, and marketing teams at other studios, put the blame squarely on the film's ad campaign, which presented it as the latest in a long run of "High School Musical"-style pictures for "tweens". Reportedly, this decision incensed the film-makers and led to many arguments as the film neared release, but the decision was never reversed.
In the original script, the band name "Glory Dogs" was written as "River Dogs" but the name was changed because in real life there is already a rock band called River Dogs- funnily enough, the real band River Dogs are from New Jersey, where most of the movie is set.
'Jason Mozersky' and Jordan Richardson were the two instrumentalists that helped with the recording of the bands' music in the film. They are now the lead guitarist and drummer (respectively) in Relentless7, Ben Harper's band.
When Glory Dogs is first performing near the beginning of the movie, Will asks Sa5m how big Bandslam is at the school, and she says "Texas high school football big". The lead singer of Glory Dogs is played by Scott Porter who played a Texas high school quarterback on Friday Night Lights (2006).
In the scene where Karen Burton is selling band shirts during the competition an actor in the background is seen wearing a shirt with, "Made in Texas" printed on the back. The movie was shot in Austin, TX.