When Kiwi is telling Jay and Terri how he feels that Sloane "yanked" his heart, we see a shot of Sloane wearing a black sweatshirt as Kiwi is telling them the story. After Kiwi says "Kiwi seal of approval.", Terri goes to the practice room to introduce herself to Sloane. In the practice room, Sloane is wearing a sweater.
When Terri, Jay, Kiwi, and Sloane sing "The Way you do the Things You Do", Terri sings alone at first. She stops to pull her friends in, but when we hear her resume singing, her mouth is closed for an entire line of the song.
When Sloan is practicing on a digital piano and her teacher is encouraging her, she is playing everything at the right time but none of the notes she plays are even close to what the audience is hearing.
When Terri and Jay are talking at the water fountain, in the close up shots, Terri has her arms on either her bag or across her chest but in the far away shots, her hand are down by her side. They keep switching in and out.
When Teri enters the auditorium to listen to Jay composing a song on the piano, he is embarrassed and gathers up the sheet music into a pile and lays it down, presumably flat. Teri turns to walk away, and Jay sits down at the piano again, trying to get her to stay. In the first shot of the background, there is no sheet music on the piano. The next shot back to him, the sheet music appears, and he refernces it with a gesture.
When Jay comes to Terri's room drunk, Jay falls to the floor and Terri kneels beside him. Someone tells them to keep quite and Jay raises up and yells something back, then, when the camera angle changes again, Jay is once again kneeling with Terri next to him
Terri and Paul's car crash is impossible. Paul is making a left hand turn through what appears to be an advance green (as the car behind them is pulling up directly behind them.) The car is t-boned, with the truck hitting Paul first. For this to be possible during a left hand turn given Paul's projected location, the truck would have to be traveling in the same direction on the wrong side of the road. There is clearly a median between the two sides of the road, making it impossible for the truck to be logically traveling there.
When Terry first arrives at school and the doors locked she looks through the door for someone, when she's doing this you can see the reflection of Jay in the window, even though he is supposed to be coming around the corner inside.