Continuity mistake: In the sceen where Kate first appears in the airport and says "How many Lizzies does it take to screw in a lightbulb..." there is a parked airplane visible in the window behind her. After a quick cut to Lizzie the scene cuts immediately back to Kate and the airplane is gone. Airplanes don't leave the gate that quickly.
Continuity mistake: If you pay close attention, Paolo's accent doesn't always stay the same. At most times, there is a clear Italian accent, but at others, an American accent can be heard.
Continuity mistake: When they arrive at the hotel, Ms Ungermeyer (Alex Borstein) says, "Welcome to hotel & 8230." During this time, she has a clipboard lying on her left forearm. Cut to a different angle (her back facing the camera) as she walks now she is just holding the clipboard with her left hand. Cut back to the previous angle and the clipboard is resting on her forearm yet again.
Continuity mistake: In the begining of the movie when Lizzie is trying to pick out an outfit for graduation, she rummages through her closet twice. The second time, you see her in a shot from inside the closet. Lizzie is wearing the outfit with the blue shirt that she changed into to sing the song. The next shot is of Lizzie from outside the closet, with her other outfit on-the one she was wearing when her brother drove his camera into her room. In the next shot from inside the closet again, she is wearing the outfit with the blue shirt on again.