On the trip to see Simons (Greg Kinnear) parents, Simon decides to talk about his family. Carol (Helen Hunt) is driving in the beautiful sunny day and decides to pull over to give her full attention to Simon (The convertible roof is down to enjoy the sun).

The next scene you see is the car pulling over with the top completely up and everyone talking as if nothing has changed.

I also believe the time factor of that conversation was off by being early day with sun over head before but down low right after but that is not guaranteed information.