When Logan is in math class dressed as a girl, the purse that he has changes position.
When Jo shows Kendall her "boyfriend," the basketball in the guy's hands keep changing position from shot to shot.
Camille had used an explosive to get the part which she didn't. It was on her right arm when she showed it to James, but when she walked out of the room after the explosion her right arm was perfectly clean.
In the beginning of "Big Time Break," in the end of the song when they run to the cover, it goes Carlos, James, Kendall, Logan, but when the cover rotates it goes Logan, Kendall, James, Carlos.
Jo confirms that she is a singer while doing judo with Kendall. However, most - if not all - of her future jobs are acting ones.