In the scenes where Early and Brian are at the bar and Carrie and Adele are in the hotel room, when Adele is painting Carrie's nails you can see the sun shining outside. When it goes back to Early and Brian, it's clearly night time.
Early Grace drinks a beer during his parole officers visit, parolees are prohibited from imbibing or using narcotics in Georgia and most US states without modification of their parole terms by the court or their parole officer.
The foursome begins the journey in Atlanta (The Georgia Dome is visible during the Breakfast Cereal Conspiracy conversation). After they've traveled 480 miles, Atlanta landmarks are still visible outside the car (Equitable building, Spaghetti Junction, etc)
Towards the end of the movie, Early violently smacks his gun across Brian's temple, above his left eye. His temple is shown in a subsequent shot as very bloody, yet there is no visible injury (or bandage) in that spot a short time later as Brian is shown driving down the road chasing after Early & Carrie.
When Early Grayce flicks the bug/cockroach from the restaurant counter onto the grill, the bug is alive when he flicks it, but it doesn't squirm or struggle when it hits the hot grill surface.
When Brian and Carrie visit the murder scene, Carrie's Nikon clearly has a motor drive, and we hear the sound of it advancing the film, but we also see her manually advancing the film.
When Early is digging the hole at night and talking to Adele, you can see the top of his pants. When he climbs out of the hole, he is obviously naked.
The amount of vodka in Carrie's glass changes inconsistently between shots while she's sitting on the couch, watching her slides, trying to convince Brian to go to California.
Towards the end of the movie, Brad and David are eating Chinese food. In one shot, you see David open his container and fold down the flaps and hold them this way. In the next shot you see him switch it with the other container on the table. When he switches it, the container he had just opened is now closed up.
When Adele pulls out of the gas station in the pouring rain, all 4 windows in the car are down. In the next camera shot, the driver's windows are up.
Early Grayce seems to be driving two different Pontiac Grand Prix in the opening scenes; the headlights differ.
When Kessler and Carrie are having sex at the motel, Carries right bra strap is alternately on/off between shots.
We first see Early's pistol laying in a bag on the car's back seat. A closeup clearly shows it to be a parkerized U.S. military World War II M1911A1 (with commercial grip panels). But later, when Early and Brian are firing it at an abandoned building, Early says it's a Japanese pistol.