Corrected entry: In the scene where Prescott asks Kevin to help him move the boxes blocking the dumbwaiter, the sounds of wine bottles moving within the boxes isn't heard. This clearly shows that the boxes were in actual fact empty, otherwise Prescott should not have asked for help.
Corrected entry: When Kevin and the butler are locked in the basement, Kevin goes up the steps to pound on the door. You can see that the hinges on the door are on the basement side of the door. Surely, there would be something in the basement that could be used to remove the hinge bolts, so they could just remove the door.
Corrected entry: Kevin could have played the recording of Marv saying he was going to kidnap the prince to his dad and girlfriend, and his problems would be solved.