Nick states that the Porsche is a 1958 Speedster and that James Dean had one just like it. James Dean died in 1955 so it is impossible for him to have owned a 1958 model. Dean's Porsche was a 1955 356 Speedster which was produced from 1948 thru 1955. The Speedster in the show was a 356A in production between 1956 and 1959. (The "Little Bastard" (the car he was driving when he crashed and died) was a 1955 Porsche 550 Spyder and is the one most people associate with James Dean.)
When Sara flips open the girlfriend's cell phone, it shows no notifications at all. Considering both her "BFF" and the Crime Lab had both tried to call her, there should at least be a notification showing the number of missed calls.