Continuity mistake: Watch Johnny's shirt collar during the scene where he first plays for Mr. Phillips. As Johnny pleads his case the collar moves, from shot to shot, from under the guitar strap, to over, then under, and over again.
Continuity mistake: In the scene where Johnny Cash and June Carter first sleep together, watch Cash's hands as Carter goes to answer the phone. In the first cut his left hand is on her bottom and his right hand is on her lower back. When the shot cuts to show Carter's face his right hand is now below her neck and his left is hand is no longer on her bottom.
Continuity mistake: During the first tour when all the guys are on the stage drinking, June throws 4 beer bottles. The last one is thrown twice because there were only 3 lying there.
Continuity mistake: When John wakes up with Waylon singing, the left side of his collar is rumpled. When he gets up to use the telephone it's straightened out.
Continuity mistake: At the first concert with Jerry Lee, towards the end of his song his white scarf disappears.