People have accused Prince of lipsinching during the Purple Rain tour because of many pictures showing no lead coming from his Hohner Telecaster and an empty output jack. The truth was that Prince had his main Hohner fitted with an internal wireless which abled him to ride onstage on his motorbike with his guitar and step off while playing. You can see the patch of black tape at the back of his guitar covering the wireless during the "Let's go crazy" performance in the movie.
Prince with one of his Hohners during the Purple rain tour, note no lead coming from the jack and the patch of tape covering up the built in wireless.