When Ethan and Hannah are at the kitchen sink, we see them from inside and from outside of the house. From the outside, we can see their faces above the curtains, but from the inside, the curtains are above their heads.
When CJ is playing the guitar in front of the audience, the soundtrack clearly doesn't match up with her playing.
A Mr. Sub sign is visible, and Shane happens to be an employee of the restaurant. However, the Mr. Sub chain is only available in Canada.