The main characters' age is depicted differently throughout the film. In the first scene, Griffin is seven years old and Sandman appears to be in his early thirties. Seventeen years later, as Sandman awaits execution, he seems not to have aged a day, while Griffin is a full grown man. However, the flashback scene shows Sandman appearing to be about 10 years old, while Griffin is depicted as a baby. Their age difference just doesn't match up.
There are several flashbacks to Griffin as a baby along with his older brother. In the first flashback in question, (first that shows the older brother walk to the crib,) his older brother's shirt is tucked into the front of his underwear. In the next flashback, replaying the same scene, only now extended further, when the brother walks to the crib, his shirt is untucked and hanging loose. In this same flashback, the camera pans away for a moment, with the shirt loose, and when it returns, the shirt is once again tucked into his underwear.
During a scene in which Griffin speaks to Dog about finding the Preacher, Dog is sitting in his car. When the camera is pointed inside the car at Dog's face, he's wearing dark sunglasses. When the camera switches to the front of the car to add Griffin and Megan into the shot, you can see Dog is missing his sunglasses. The camera switches once again to the driver's side window, placing only Dog back into the shot, and still, his sunglasses are missing.