The scene in the beginning of the film between Kale and his father was improvised, as well as the scene between Kale and his mother when Kale discovered Mr. Turner's dented fender.
When Kale presses the menu button on the Xbox controller, he's supposed to be offline, but you can see that he has 2 new messages button and that there are 2 friends online, so he's still online.
When Kale breaks into Mr. Turner's house with the garden shears, he cleanly knocks out the full pane of glass. But, when Officer Gutierrez responds to the call, he sees large shards of glass still in the window pane of Mr. Turner's house
When Kale gets the text message from Ronnie to "look at his TV", the phone icon on his phone is on vibrate mode, so he shouldn't have heard the "Me So Horny" ring-tone.