Revealing mistake: When H.I. runs away after a robbery, you can see very fresh tire tracks made by the camera car on the wet pavement. The street was deserted, so the tracks couldn't have been from another car.
Continuity mistake: I'm no expert on accents. But why does everyone sound like they're from the Deep South and not the Southwest? As far as I know, Arizonians don't have a twang like the characters in the film do.
Continuity mistake: After Glenn has informed HI that he will be back to take the baby, he peels off in his station wagon. The tires show a large black patch, free of dust, where it was contacting the ground prior to pulling away. The rest of the tire and car was dust covered.
Continuity mistake: When H.I. is robbing the convenient store to get cash and Huggies, it's been raining as the streets are wet, but the parking lot of the convenient store is bone dry.