I think that the teams were headed from Chenonceau to Normandy.
The first tweet from France which mentions the Amazing Race filming was about 6 hours before the Chenonceau tweet, but her last apparent location was Mont Saint Michel. Of course, our first tweeter may have been somewhere else, even Chenonceau. But given the route so far, it seemed strange for the second tweet to be coming from several hours south of the last known spot of the first tweeter. So, I think that first tweeter may have seen Phil doing his stand-ups.
There is a lovely chateau and hot-air balloon museum in Normandy about an hour and a half from Mont Saint Michel called Chateau Balleroy, and a notice on their website roughly translates to "Exceptional closing of chateau Friday, June 15 16h to 14h Monday, June 18. The museum balloons and park remain open." If I am reading twitter times correctly, the first tweet comes shortly after that closure. Given the time frame of the closure, if they were headed there, I think it is a pit stop. I doubt they will be there that long, but they may have booked some wiggle room.
Chances are it's closed for a completely unrelated event, but it sure looks like a place the race would use.