I am having trouble imagining doing something like this with tools that were available when the races originally aired. Street View is a tremendous help, when it is available. Panaramio photos can provide great supporting evidence, though they can also be misleading because they are not always precisely placed.
Also, a fresh re-watch means that I can sometime pick up details that I missed or didn't remember from before. A non-relavent but interesting example: it appears that the during the early morning departure from Kasteel Muiderslot in Race 4 leg 6, the same driver appears to have picked up Millie and Chuck, Monica and Sheree, and Tian and Jaree.
Since the above posting, I've modified one route marker, the Tunisian Desert roadblock. In considering it, it seems unlikely to me that the racers would have been required to make a seven-mile trek across the desert. Locating this off off Piste Ksar Ghilane Douz would make the walk/camel ride about a mile and a half, and that makes more sense to me. Also, I've made a few minor tweaks to the annotations spreadsheets.