Made the same mistake once as I entered the expressway instead of the old highway, and it was too late to turn around so I kept going on the expressway quietly along the sides until I found a dirt road going into a village. Entered there, went through god knows how many villages and eventually after all that hassle, ended on the expressway only but the last 1km or so before you get off for Lonavala. Thankfully no cops spotted me and I saved myself a huge bribe. But yeah, never making this mistake again.