When the star and the publicist arrive at the house, the hand with which the publicist shakes hands the hero's hand switches from left to right between the direct and reverse shots.
During the prom, David was told by another character "I thought Alex was going to be your date." David's explanation was that some rule kept her from being able to attend the prom. Alex's unpromposal did not mention anything about a rule preventing her from attending, but simply stated that she couldn't be there due to circumstances beyond her control.
Mr. Walsh gives Alex a driving lesson because she confessed that she never learned how to drive. She said she always takes limos. Just a little later, Alex tells Mr. Walsh about her early career and arrival in Hollywood. She said when she arrived in Hollywood, she lived out of her car for a while. Usually, when someone is living out of their car, they know how to drive.
Alex said she moved to Hollywood with her mom, so Mom might've done the driving.