Revealing mistake: There are no keys in the Jeep when we see the breakdown happen. You can see the steering wheel and where the keys should be. How is this car even moving? (00:08:05 - 00:08:35)
Revealing mistake: When Kurt is being chased after in the truck at the end, he pulls out onto the main highway and the truck skids. There are several tire marks where they practised this skid before. Also, at the very end when the truck is being pushed by the semi, look ahead of the front truck tire, more previous tire marks. (01:21:20)
Revealing mistake: During the ending sequence, just as J.T. Walsh is pushing the truck on the bridge, there is a shot looking at the front of the semi and you can see that it is not J.T. Walsh driving. The stunt man is noticeably heavier than J.T. is, and his hair is messier.
Revealing mistake: Near the end, when Kurt Russell and his wife are in a beige utility truck which is being rammed through a bridge railing by the semi-tractor, there are at least two close up shots in which miniature models were very obvious.
Revealing mistake: When Jeff and Amy are being chased by Red near the end and Red's truck begins to jackknife, you can see how they made the trailer slide in that direction. It seems that they constructed or used a trailer that had a set of wheels that would turn. They were turned in the direction of the slide.
Revealing mistake: When Kurt is floating down the river after escaping the vehicle, his shirt looks much bigger than normal, indicating he is wearing a flotation device.
Revealing mistake: When Kurt Russell is climbing the side of truck you can see a fence revealing that they are parked, even though wind is blowing to make it look like they are moving.
Revealing mistake: During the chase on the dirt road, Jeff pulls the Jeep up to the edge of a cliff. Look at the ground ahead of where he ends up. There are clear tire tracks, and the Jeep follows them to a T. This was obviously where they practiced the scene before.
Answer: There was always a ransom, or at least that was always the intent. Anyone that didn't have money the kidnappers would just eliminate them. The kidnappers MO was to take a couple and force one of them to empty their bank accounts. Earl makes it clear that the difference in Jeff's case is that they were unable to kidnap the pair at the same time. For whatever reason, Jeff refused to get in the truck with Red, which caused the kidnappers to alter their plans slightly. Earl also gives some insight into how the group chooses their victims. He tells Jeff that he was targeted because he was driving a brand new SUV, which indicated he must have a fair amount of money in the bank. The kidnappers care very little about being caught, they have obviously committed many murders without being found out. They seem to leave very little evidence of their crimes for the police to find. Red is always several steps ahead of the police and is brazen enough to kidnap a man's wife and say directly to him in front of a police officer that the man must have him mistaken for someone else.
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