Continuity mistake: When she's talking to the guidance counsellor, in the close-ups we can see some stadium lighting outside the window over the counsellor's shoulder. In the wide shots it disappears, and is replaced by the sea. It's definitely the same window - the ornaments on the window sill are the same, and the plant to the right is the same.
Continuity mistake: When Patrick sings to Kat during her soccer practice, after the band does their solo and Patrick begins to sing again, the camera shows a close up of Kat in which her teammates follow closely behind her. The camera goes back to Patrick then back to Kat, this time her teammates are still following her but they are further back. After another flip to Patrick the camera flips back to the girls who are back where they were the first time.