When the grandma is in the kitchen, she has a head manikin in front of her but when the camera switches off her to Ryden's mother and back to the grandmother, the manikin is now different and behind her.
During the concert, Adam picks up an electric sunburst guitar, the shot then goes to the crowd and back to him and his electric has become an acoustic guitar (around 53 minutes).
At the graduation, all the graduation caps have the year '08 on them, but the banner behind the valedictorian reads 2009.
When Ryden is giving the bags to Jessica, after looking at the last bag, she storms out the store never really putting the bag back on the shelf.