During the dance sequence for "That's the Way (I Like It)" Kelly's shoes change twice. At the beginning, she is wearing open-toed black shoes, which turn to sneakers for about two seconds, then back to open-toed shoes. At the end, she's wearing sneakers.
At the beginning, during the dance scene on the beach, Kelly is holding a ball that disappears and reappears between shots.
When the girls are leaving the beach, Alexa gets the first text message from Justin. They show her phone up close, and you can see her phone has no antenna. When she puts her phone back in her purse, the phone has an antenna.
When Alexa is talking to Justin, he is right next to a half-full drink with a lime slice on the rim. When Kelly walks by and sees Justin talking to Alexa, the drink is almost full.
Kelly finds out that Alexa has been texting Justin, and walks away without her purse. In the next scene, Kelly starts singing "Anytime," while walking and carrying her purse.
When Justin is talking to the girl sitting under the canopy at the beach, set crew, monitors, and lighting are visible in background.
When Brendan is being chased by the "steroid freak" on the beach, he is running between the tire tracks of the camera truck.
When Kelly gave Justin her phone number, she used an area code from Texas (972), which is where they are all from. But when Alexa later gave Justin a phone number for Kelly, she gave her own cell phone number. She used the area code 239, which is actually in Florida.