Jessica Alba found that no one on the cast and crew would look her in the eye when she was in her full beaten-up make-up. The prosthetics were suitably graphic and off-putting that people were loath to talk to her.
Early in the movie when Max is thanking Lou for what he had done for his Johnny - Lou is wearing a hat which beneath you can clearly see a curly piece of Lou's hair coming out from underneath. Then in the next shot the hair disappears under the hat.
In the beginning of the movie, when Lou is driving his sheriff's car down town, he says "I was born here 29 years ago, and central city is small enough that my father..." You can see an modern day USPS mail truck in the reflection of the building window.
Lou Ford: I got a foot on both sides of the fence. They were put there early, and they stayed put. I can't move. I can't jump. All I can do is wait until I split, right down the middle.