Continuity mistake: During the police car challenge, Richard Hammond is taking his homemade police car around the track on a timed lap (with extra points for flamboyant driving). As he rounds the Hammerhead corner, the makeshift stinger (that's a spike strip for the colonials) on the front of his car breaks off and is left behind. He then drives through a stack of boxes, getting one caught on the remains of the stinger mounting. As he approaches the second-to-last corner, the box has gone and the stinger is now back on the front of the car. In the final shot as his car limps across the finish line, the stinger is once again missing and the box has returned. Clearly footage from a different lap was substituted in. (00:51:10)
Continuity mistake: During Jeremy's timed lap in his police car, Richard and James watch him go from the start/finish line. But, when James comments about Jeremy having unbalanced the wheels, they are standing in a completely different part of the track. They then return to the line as Jeremy finishes.
Suggested correction: This isn't something they hide. Behind the scenes interviews make it quite clear that they have a B unit that films additional footage of the areas they travel in. They even take the cars back to get more shots of them on the road, since they can't predict the exact routes that will be taken in order to have camera crews ahead of them in time.
The mistake is perfectly valid. The correction is only providing an excuse as to why the mistake occurs. Most shows/films have a second unit director and crew (the "B unit") solely to film supplemental footage. This does not invalidate the point of the mistake, that "their very distinctive cars are not on deck" where they should be.
Super Grover ★
Since they cut to and from shots of Hammond, May and Clarkson standing on the deck of the boat the implication is clear - the shots are continuous. It is a glaring error.