Continuity mistake: In the scene where Owen uses the computer for the first time, we see that he's using instant messenger service. We see that he types "Ooh, I'm scared". However, later we see the message and now, instead of "Ooh", it reads "Oooh" (notice that now it has three "o", and before it had two). He couldn't change it, because the messages can not be edited when they're posted in an instant messenger service.
Continuity mistake: In the scene where Owen and Tom pull Dodger from the pool. We see that Dodger's hair is hanging down over her face. We then see Owen's reaction, and then we return to Dodger. This time we see that her hair is behind her ear. She didn't have the time and it wouldn't make sense that she changed the position of her hair.
Factual error: Owen's phone is a Nokia 3300 which is one the phones which are designed to be wider rather than taller (like an N-Gage). Throughout the film when Owen speaks on the phone he holds it the wrong way around. He holds it to his right ear with the rounded edge of the phone pointing upwards to the top of his head. Holding it this way would mean he'd have the microphone to his ear and be speaking into the speaker. I noticed this because I have the same phone, obviously the actor was not sure which end was which and guessed, getting it wrong. I noticed this during the scene where he phones the girl that got stood up at her dance.
Regina: I hate to be the bitch but are we gonna play or what?
Tom: Aw Regina, you love to be the bitch.