Continuity mistake: When Jim pushes John out the car, in the shot where John is lying on the road, his head is on the road's white stripe, yet when it cuts to a closer view, his chest is on the white line, not his head. (00:12:30)
Continuity mistake: In one scene C. Thomas Howell almost runs head-on with an 18 wheeler, but just misses it. However, the truck clips the car he is driving and clearly takes the bumper clean off. The next driving scene shows the bumper back on the car.
Continuity mistake: Towards the end of the film, the bus that Jim sneaks on to changes from two rear axles to one.
Continuity mistake: Just after John throws Jim's keys back to him, Jim is driving along the road and gets hit from the back by John. Jim spills coffee on his cheek and neck, but in the following shot nothing is there, and he couldn't have wiped it off between shots. (00:19:10)
Continuity mistake: When Jim is driving along the road, the car with the boat on the back passes him. When John appears, Jim pulls out onto the other side, and the road is just flat with sand and grass, yet when it cuts to a face shot of Jim there are now large mounds of mud, or something, at the side of the road. (00:14:05)
Continuity mistake: During the scene where Ryder has a knife to Jim's throat and is asking him to repeat "I want to die", you can see through the passenger window behind Ryder that morning is starting to break. About a minute down the highway when Jim and Ryder come upon the construction zone, it is now black as night again.
Continuity mistake: When John has just dived into the Sheriff's truck from the prison truck, and tells Jim to drive, Jim accelerates, then brakes hard, to throw John through the windshield. As Jim brakes, John's left hand is holding the shotgun, and his right hand is holding Jim's lapel. In the next cut, as John goes through the windshield, the shotgun is in his right hand. (01:30:20)
Continuity mistake: When Nash is talking with Jim in the restaurant where she works, she is holding a flask in her left hand the puts the flask down, but in the following shot it appears in her right hand. (00:27:10)
Continuity mistake: When Jim is being questioned at the police station, the guy phoning Jim's brother has his hand on the phone or by the phone, then he moves his arm away, but in the following shot his hand is still on the phone. (00:33:00)
Continuity mistake: After Jim picks up John, they see a VW Beetle that's on the side of the road and its position changes in the next shot. (00:05:30)
Continuity mistake: When Jim is being asked questions in the police station, the cop with the blue denim jacket puts his hands on the chair in one shot, then they're not there in the next shot, but back in the shot after. (00:32:30)
Continuity mistake: C. Thomas Howell has a mole-like thing on the left side of his chin, that appears, disappears, and fades between shots.
Continuity mistake: When John dives from the prison truck into the sheriff's truck through the windshield, the stuntman drops the shotgun as he impacts the glass. We even see it bouncing into the back seat. But in the next cut, John has the shotgun firmly grasped as he lands on the seat. (01:30:00)
Continuity mistake: When Jim eats at Nash's workplace, in one shot there is no napkin, knife or fork in front of Jim's plate. Then when Nash walks away it cuts to another angle, and now there is a knife and fork on a napkin. (00:28:00)
Continuity mistake: When Jim stops for coffee in "Roy's Cafe," John sits opposite him, and if you watch closely in one of the shots, the plant behind Jim gets knocked over, yet a few shots later it's back upright standing in its container. (00:49:15)
Continuity mistake: When C. Thomas Howell is looking in the mirror, in the shots taken from above the mirror, it is not that dirty. Yet, when it cuts to a close up of the mirror, it is filthy.
Answer: What you see him playing with is a link on the chains around his waist - note chains, not handcuffs. We know he's a resourceful guy, and just before he escapes, we see the two guards playing cards, with the shotgun loosely on one's lap - based on what we know about the configuration of the truck, John would have easily been able to leap forward and grab the shotgun while we see Jim driving up to the truck. John then shoots the guards with the shotgun we now know he just grabbed.