Police is really checking whether you would be leaving Prague district. That was a reason to turn back at point 13. Újezd u Průhonic is still Prague, Průhonice village is not. So after the restriction will be lifted, you can extend the trip to go around the Průhonice park and through that village. If you will be riding around here in couple weeks, in April and May, you may try to visit Dendrological garden, which will be in full bloom. For that you would turn left at point 12 and then right at the end of the fence. This way you will arrive at the entrance and will be happy that you have only bike to park. There will be too many parked cars.
This ride started at the parking lot at Opatov, where you will find the spot all the time. Parking fee is Kč 20. Bike path is well maintained, the attention should be paid between points 6 and 8, where it is quite narrow and you may meet there a lot of people walking. From the point 11 to 12 you may choose the simple wide path, or, if you like some adrenaline, you may follow narrow path along the stream of Botič. In this case be careful and maybe walk your bike for several meters through the most treacherous pieces.
Do not miss the view of two emus at point 8. They are quite friendly and like to pose for a photo. During the ride through the Milíčovský les and over Milíčovský vrch (14 to 19) you may see a lot of people since this is quite popular walking area.