When Neal wakes up in the hospital, after delivering the package, he finds a playing card in a flower arrangement. As he looks at the face of the playing card, the back is clearly visible to the camera right-side-up. When he flips the card over to view the back, the back appears right-side-up to him, instead of correctly up-side-down.
Zack & Bob Cody are driving West on Interstate 60 and the Sun is on their left, illuminating the left hand side of the car. Change camera view. From behind the car. The Sun is on the right, casting shadows to the left.
When Neal wakes up a couple of times in a hospital bed his pupils are dilated differently. The pupil in his right eye is more dilated than the left. his right eye is in less light than the left so, that would explain why however, he's meant to be wakening from a long sleep so, you'd expect both pupils to be equally dilated. It could be that the pupil dilation is affected through the eyelids.
Zack & Bob Cody are driving West on Interstate 60 and the Sun is on their left, illuminating the left hand side of the car. Change camera view. From behind the car. The SUn is on the right, casting shadows to the left.
The rope barriers along the ground leading to the desk in suite 1300.
(at around 3 mins) Zack looks at the US Midwest on the map and points out I-64, I-65, I-66 and I-69. However, I-66 is only a short segment running from Virginia to Washington, D.C., nowhere near the area Zack is pointing at.
If Zack & Bob Cody were travelling West on Interstate 60, the Sun could NOT have been on their right.
Ray stacks the cards on top of each other in the four stacks while Neal calls out the suits. The third card called was spade and was in fact the 3 of spades. The next card called was hearts and in fact was the 5 of hearts.
He grabbed the stacks from the bottom when he flipped them over. The cards shown were the 6 of black hearts and 5 of red spades.
A helicopter shadow is visible during the opening credits.
When Neal smashes the Magic 8-Ball, the sound of breaking glass is heard. The 8-Ball is made entirely of plastic.
Seconds after Neal wakes up in the hospital after being knocked cold, clearly disoriented and unsure where he is, his sister comes in. He tells her the doctors want to "keep me overnight, to log some tests in the morning." How does he know this?
The website Neal calls up at the beginning of the movie is misspelled as "majordesicion.com" (the correct spelling being "decision", not "desicion").