That's something I'm starting to do as well - you lose track of time when searching in the bush for caches...(or the perfect photograph!) I may pick up a radio for that purpose, a few places I have gone caching have zero mobile reception.
This past weekend I didn't make it off a local mountain before dark - thought I was on what should have been a clearly marked trail, and ended up on a deer trail (I saw deer!) that practically disappeared in both directions. When I did get off the mountain, I had to cut through someones yard (I hope they forgive me), and then walk on a complaining ankle (from a stumble in the dark) 2.5 kilometres back to where my car was parked. Thankfully this park doesn't lock the gates until 11pm, I had time to spare.
It took me about 15 minutes after arriving at my car to calm down enough that I felt OK to drive home. I was half dreading, half praying the RCMP would come by. I'm pretty sure after I got over my initial embarassment over how monumentally bad things could have gone - I'd have been pretty damned thankful to see them!