Factual error: In the scene where Ms. Ungermeyer returns to the hotel and takes the elevator upstairs, Sergei detains her in the elevator (to give Lizzie time to get into her room) while the classmates, including Kate, walk up the stairs. Since the rooms were on the first floor, Kate should have reached her and Lizzie's room before Ms. Ungermeyer; however, they enter the room at the same time.
Factual error: When Lizzie was performing, there's no stairs in the shots of the crowd.
Factual error: In the scene where Paolo first meets Lizzie at the Trevi fountain, wouldn't he be swarmed by an army of photographers or at least a bodyguard or two? A popstar as famous as him probably couldn't go out alone in public like that.
Answer: No one knows for sure, but he likely lost his career and faced a lot of lifelong humiliation as have previously singers who were found to be secretly lip syncing to someone else's voice.