When Nelson Beterman IV is in the courthouse, you see John eating popcorn. In the first shot, you can't see the popcorn in the bag, but in the second shot, the bag is full to the brim. Again in the third shot, the popcorn is lower in the bag.
When Nelly is washing the phrase "White Power" off of his head, you clearly see it going away. The next scene in the lunch room you can see "White Power" still written on his head. The following scene it's gone.
When the drug dealer in jail pulls out the boat cleaner, the blue fluid is in a jar. In the next camera angle the blue fluid is in a bottle.
When John Lyshitski shoots the phone booth after learning of the death of Judge Biederman, two more shots sound after the pistol stops firing.
Early in the film when Nelson is driving from the park dedication, his yellow tie appears in various stages of being tied and loosened.
Barry visits Nelson in prison after being paroled. In reality this could never happen as a parolee cannot visit an inmate.
When Nelson Biederman IV first goes to cell, he starts crying and leans onto the wall, the wall shakes.
When John ravages his cell, the wall he is kicking moves.
Early in the movie, when John is driving his truck, you can clearly see there are no keys in the ignition.
As Nelson's pen pal reads the letter to his class, two of the kids can be seen looking at the camera as it pulls back for a wider shot.
When Nelson punches Barry in the bathroom, you hear the second punch before contact.
At the end of the movie, when the three are driving off in the car, the shadow of the camera mounted on the vehicle is quite visible in his face.
Dispite Nelson having a bad asthma attack that leads to him ending up in prison, he doesn't need an inhaler for the remainder of the movie.
The Korean Pharmacist is speaking Tagalog, the Filipino language.