She's the ManGoofs
Crew or equipment visible
Errors in geography
After one of the teams scores a goal in the final soccer game, they are seen putting the ball back into play by way of corner kick; In a real game of soccer, after one team scores a goal, the other team puts it back into play with a kick-off: Kicking the ball from the center spot on the field, used to start the game and the second half.
Incorrectly regarded as goofs
In the weight room, when Duke and Viola are talking about Duke asking Viola out, Olivia can be seen in the corner of the shot on a machine, watching. In the next shot, someone who looks like her is on the treadmill. In the commentary, the actors and director mention that this was a different girl, and they didn't know why she was dressed the same.
Viola takes her brother, Sebastian's, place by posing as him for 2 weeks at Illyria while he is in London. Viola is enrolled at a different school, Cornwall. No explanation is given as to how Viola is able to stay enrolled at Cornwall and get away with missing 2 weeks of classes. Multiple absences would result in a phone call to the parent/guardian and disenrollment would require their authorization.
Towards the beginning of the movie, Viola (as Sebastian) is called to the principal's office. She then looks in his filing cabinet for her brother's school files and when she hears the principal open the door, she slams the cabinet door shut, catching her breast-reducing wrap in the cabinet. When she goes to slam the door, you can see Amanda Bynes' eyes look directly at the wrap, making sure that it is in the cabinet well enough to get caught.