When driving on roads which were not closed for filming, Tom's Mercedes-Benz CLK has a plate from Stuttgart, it is a free gift from Mercedes-Benz.
At least two different silver Ford Mondeos were used during the first chase: When it gets stuck underneath the concrete body, it has a different grille than when he rushed through the rush hour traffic a few scenes before.
When it is crashed, it has a huge hole in its windshield, which is gone during the final scenes of the crash.
The black Rover 800 which gets involved in the pile-up has no badging on the trunk lid. In a flashback scene later, the letters "ROVER" are visible.