The exterior of the limo that is shown taking Sebastian and Kathryn to school changes from the time that it is initially shown to the time it is seen in front of the school. The first limo shown has different rims than the one that shows up in front of the school. The first limo also lacks the chrome trim around the bottom of the doors that the one that pulls up in front of the school has.
When Sebastian gets up from the bed, he has chest hair. While heading towards the shower in the bathroom, the chest hair is gone and he has lost a lot of weight. This is because the shower scene with the lesbian twins was filmed over a year after principle photography ended.
When Sebastian's father is on the phone to his "accountant" and Sebastian walks in, to the right hand side of the screen above the sofa his father is sitting on, you can see the head of a crew-member in the whole shot.