Continuity mistake: In the scene where Thunderbolt and Lightfoot are in the car with the crazy driver. The car goes over the embankment and as it flips you can see a wheel break off. A short time later they both drive off in the same car, with the wheel attached again.
Continuity mistake: When the girl is yelling rape at the motel, she is wearing a bra and panties. After getting some money for a cab, she puts on her dress and she is bra-less.
Revealing mistake: When Clint Eastwood and Jeff Bridges are being chased by George Kennedy and his partner, Bridges is driving off the dirt road down and embankment and you can clearly see that in the passenger seat is a faceless dummy instead of Eastwood or another stunt man.
Answer: Since the crate was labelled machine parts, I'm guessing fraudulently.