During Rosie's first night in Louisiana, characteristic sounds of the Coqui frog ("Coqui, Coqui") can be heard in the background. This frog is native to Puerto Rico and is known to have spread to Virgin Islands, Dominican Republic, and Hawaii, but not Louisiana.
Chelsea is seen in the frozen yogurt store, and outside in the car in successive shots. These shots are not happening simultaneously, but indicate a passage of time to show how long Chelsea left Rosie to suffer in humiliation.
When the girls arrive at the bowling alley Ed says to Carter that he would get her shoes he said "5 1/5 coming up" but when they return the shoes the camera gets close to the real size on the shoe and it says size 7/8. Therefore Selena Gomez wears a size 7 or 8 shoe, not a 5 1/5.
The goof item below may give away important plot points.
Incorrectly regarded as goofs
Though it creates suspense for a possible sequel to the film, the ending doesn't seem to make sense. How can Queen Rosalinda serve as an active field agent while performing the necessary duties of governing her country? She can appoint her mother as a regent or even convert her country into a constitutional monarchy, in which the queen has much less duties, if any at all.
When General Kane is caught kidnapping the Princess, the Director says that Kane will be turned over to the international authorities. This seems unnecessary, as Kane can be prosecuted under the US law under such circumstances. However, the Director never explicitly states that Kane is wanted only for kidnapping. It is possible that during his revolution he committed crimes against humanity or otherwise broke some international law, for which he can be prosecuted after being caught outside of his country.