ALso extra spot lamps were added in the tunnel scene, watch it you will see they have extra ones in a couple of frames.
I think that is mainly because they had so many Minis to use and destroy in the film.
For a start they did attempt the wall of death in that tunnel (which is a sewer in Coventry I believe). But due to a ledge or holes for light fittings the Minis ended up on their roofs and were pretty much destroyed.