When Elle is leaving the airport on Noah's motorcycle, it appears the she kickstarts it. This motorcycle doesn't have a kickstarter as this is a late model Honda shadow VT750. This model uses an electric start and the switch is shown several times on the handle bars.
The movie is supposed to take place in Los Angeles, but when Noah is driving Elle home from the beach, a sign reading 17c is visible, which represents 17 degrees Celsius. Fahrenheit is used in the U.S. but many digital signs such as this switch between time and temperature in both Fahrenheit and Celsius. The background scenes are clearly in the Los Angeles area.
Obvious stunt double for Ellie when she rides Noah's motorcycle.
When Lee is talking to Elle about dating Tuppen he is holding an In N Out burger. It is obviously not an In N Out burger because it has sesame seeds.
Elle's scar changes cheeks. When she was first injured it was on her left cheek. At the prom the scar is on her right cheek.