When Tracey and Finnigan are in the car and "Will You Still Love Me" is playing, at one point he turns off the radio to talk to Tracey. When he turns the radio back on, the song continues from where he turned it off like it was a tape instead of a live broadcast.
"California Dreamin'" by The Mamas & The Papas came out in January/February of 1966 but it's played on the radio and sung as a duet by Pirate & Sunshine in the summer of 1965.
At one point the narrator in talking about the Watts Riot speaks of the assassination of President Kennedy happening the year before. The Watts riots happened in August 1965 and the JFK assassination happened in November 1963, which would place it almost two years earlier, not one as stated.
The film is set in 1965, so it's unlikely Pirate would have heard Tim Hardin's "A Reason to Believe" which wasn't released until 1966.
Set in 1965, a poster for "The Endless Summer" can be seen in Stick's bedroom. "The Endless Summer" wasn't released until 1966.