When Harold and Kumar arrive in Texas, the rear license plate on their car is a Texas plate. The car's front plate is from Virginia when they are in front of the whorehouse. The rear plate changes back to Virginia once they get to the house. When Harold and Kumar arrive in Texas, the rear license plate on their car is a Texas plate. The car's front plate is from Virginia when they are in front of the whorehouse. The rear plate changes back to Virginia once they get to the house.
In the beginning, Harold has a damaged face and a bandage on the top on his head, but when they arrive on the plane about 2 hours later, his face is not damaged at all and his bandage is gone.
The back passenger window gets blown off by the shotgun in the whorehouse. But in a later, different scene, the window is still there, just rolled down half way.
At the beginning of the movie when Kumar is on the toilet you can see his gray underwear, which should have been pulled down when using the toilet.
When Kumar peels out backwards at the whorehouse, you can see the tow line attached to the undercarriage go slack. It disappears when the camera angle changes. It's also a revealing mistake in that it shows how they were able to do the stunt with the actors in the car.
At the prison, the 'Specialist' rank on Big Bob is upside down.