I sortof got lost one day - we call it the "3 hour tour". Had planned on doing a 3 hour ride but found a trail and my buddy and I decided to see where it went. Level heads would have told us to turn back after a awhile but it soon became a mission to see how far the trail went. We climbed and climbed (and occasionally walked as the trail got narrow, rocky and well "Iffy") and climbed and eventually came to the other side of the Santa Ana Mountains hell and gone from my start. We took some surface streets back in order to save some time but eventually got on a trail system I've not ever ridden, got lost again, thankfully ran across a runner who told us where to go (thank goodness cause we were headed in the wrong direction). We finally made it back to the original trail and back to the cars. Had planned on a casual 20 mile, 3 hour ride and instead did close to 45 and took almost 8 hr. (there was some trail blazing and walking involved). I had only a Balance Bar and a half Camelbak of water. That was foolish. I got bonky and thirsty. I now don't trail blaze unless prepared.
A couple of times riding trails in Mammoth I got lost but learned to get to a high point, spot the Mountain and work my way back. It did get alittle scary at times as they are sometimes strange people lurking about.