When Eileen returns home from the FBI and checks the mail, see grabs the top two letters from the pile, but in the next shot she has three letters in her hand.
During Wayne and Eileen's breakfast by the pool, while Wayne is trying to teach the dog to jump in the pool, the orange juice level in her glass changes between shots.
Wayne's new, white sneakers started looking less new and white, but when Wayne tries to escape and is running through the rain and mud, the sneakers look very white.
When Wayne is telling the story in the forest about his father dying the sticking plaster (put on from an earlier fall) is not there. A few scenes letter the sticking plaster is back on his eyebrow.
When Wayne is leaving the table by the pool, he picks up his jacket. In the next scene just a second later, he picks up the ball to the throw to the dog and his jacket is on. There is no way he would have had time to put on his jacket.
When Wayne Hayes is approaching the top of the hill and it begins to rain, his right shoulder appears slightly transparent.
When both men are climbing through the woods, Wayne pauses to rest, and Arnold cocks his handgun and discharges it, aiming for, and hitting the trunk of a nearby tree, to show that he means business. The sound overdubbed is the distinctive sound of a hammer being locked into position, consistent with a revolver, but the handgun Arnold is holding is actually small automatic. The sound effect should be that of a 'rack and slide'.
When Eileen returns home from the FBI and checks the mail, two identical looking business letters are visible that both have "Pittsburgh, PA" spelled without h in the recipient address. On the first letter the same mistake can also be seen in the sender address.