When Hannah and Lola jump into the ball pit, about 15-20 balls are knocked out of the pit. But when the crowd reaches the pit, the balls have disappeared.
When Hannah sings "Who Said", she is holding a black microphone with a black tip, but when she ends the song, she is holding a black microphone with a silver tip.
When Hannah gives Sarah the money her fans raised, Hannah's jacket is zipped half way up. In the next shot, when Sarah faints, Hannah's jacket is unzipped, then in the next shot her jacket is zipped up half way again.
When Oliver is holding the money that Hannah pulled in from the concert, as the camera zooms out from the cash, you can clearly see the words "For Motion Picture Use Only" printed on the bills.