In the song 'Ultraviolet' the singer's guitar changes from an acoustic guitar to an electric guitar back to an acoustic guitar.
At Georgia's party, Lindsey pulls the power cord out during the song 'Ultraviolet' and then goes on stage to talk to the crowd through the microphone, which shouldn't work due to her pulling the power.
Maybe she just dis-connects the guitars from the amp, but the microphone is still plugged in.
Georgia accidentally shaves off part of her eyebrow, then uses her hair & makeup as a disguise. After an uncertain amount of time early in the film, it quickly grows back.
When Tom is wrestling with Angus in the park, his shirt is unbuttoned. When the four of them are talking together, his shirt is buttoned. Then when he asks Jas out on a date, his shirt is unbuttoned again.
When the Ace Gang first meets, Rosie is passing around lip gloss. When Georgia gets it, she has it in one shot, talking to Rosie, but when the camera goes back to Rosie, she is holding it again.
When the girls are playing netball, when Jas and Georgia are arguing, for a brief moment Georgia is shouting at an extra.
When some of the Ace Gang are sitting behind the bushes, the plastic mat that they are sitting on is visible in the corner.
When Georgia is walking toward Robbie on the beach, you can see her battery pack under her hoody. When she sits down next to him the battery pack is gone.
When Georgia opens the fridge, you can see a carton of eggs in the fridge. In the UK, people do not refrigerate eggs.
When Robbie and Georgia are walking towards the camera at the end of the beach scene, you see Georgia briefly look into the lens. Georgia Groome mentions this in the DVD Commentary.
When the girls are stalking Robbie and Tom on the ferry, Ellen clearly messes up on the dance they are all doing.
When the girls are rating each others looks, Ellen is eating pizza, but misses her mouth.