Revealing mistake: After Mitchie wakes up at the start, her hand slides across the keyboard keys in the close-up, but that hand is not Demi Lovato's. The older looking hand has protruding veins and the fingernails are long, whereas Mitchie's nails are short and her hands look as young as she does.
Revealing mistake: When Peggy is on stage performing, she is only using one hand to play her guitar (to strum) but she doesn't use her other hand to change the notes yet we still hear the notes changing. . .