While at the Dean's house, Ashley asks Shaun about his brother's aspirin (drugs) and Shaun reacts shocked and nervous as if he somehow already knew she gave some to the Dean, but he was out in the car obtaining his transcript when she did that - so obviously he would not have known.
When the mother is taking the pillows off the bed she takes the same pillow off three times.
When Bud leaves the house to discuss getting a divorce with Krista, there is only one car parked at the house, a Nissan Pathfinder (Shaun's car). There is no car belonging to Bud parked in or around the house. Bud mentions he drives past the house on his way home from work. But where is the car, and how did he get there?
When Shaun goes to ask his father for help in getting into Stanford, his father is wearing a grey sweater. A short while later he is wearing a black shirt.
When Jake jumps down off the table, you can see a paw on Bob's lap from a second dog that was removed entirely from the movie.
At the end of the film when Shaun and his friends are on the beach, he decides to take up surfing again. Shaun and his friends pick up their surf boards and run towards the water. However, the sun is setting and the sea is really calm. There are no waves at all, not even a ripple.
At the end when they run to go surfing the sea is completely flat at sunset. Not one wave in sight.
When 'Lupe' is talking to Shaun, the subtitles read: 'Double pay on weekends?' while her mouth is saying 'OK'
Although the film is supposed to take place in Orange County, none of it was shot there. All locations are in Los Angeles County.
The kid talking to Ashley at the party mentions that he got 50 bonus points for his use of the word "mazer" in Scrabble. 50 bonus points are awarded only when a player uses all of their letter tiles in a turn. You have 7 letter tiles per turn, so there is no way he could have received the 50 points under the rules of Scrabble.
When Lance is talking about his t-shirt idea, his hand moves across his chest the opposite way that the words would be going.