The TV cameras at the Jamboree have a "W" call-sign on them. Since they are supposed to be in Los Angeles, it would be expected that they had a "K" call-sign.
The poster for the Rock and Roll Jamboree later in the movie lists Lisa and Jimmy James as an act. Their names should be Lisa and Jimmy Johns.
When Lisa Johns is being interviewed by Corinne Talbot at a street side diner, you see the same woman in a fur coat walk by the window (twice) while the same car and transit bus (twice) go by the window after the traffic signal changes.