When Tania the transsexual stripper talks to Jesse and Chester the road in the background is dry, when the cops pull up the ground is wet. It's true that cinematographers love wet roads, but there has been no rain.
When Mr. Pizzacoli walks into Jesse and Chester's house, out the window there is a driveway, but when they leave their house, there is no driveway. This also happens when the twins come over to break up with them.
When Jesse and Chester are speaking with Nelson, Nelson stands up to stop the wind chime. We then see Nelson's dog, Jackal, smoking his pipe, with Nelson sitting down in the background. The following shot shows Nelson standing again.
When Jesse and Chester are taking out the trash in their girlfriends home, Jesse takes off one shoe and Chester takes off one shoe and sock but directly after when they drop the trash, you can see they both have their footwear back on, and in the next shot, when thrown outside their footwear is off again.