This update should fix the problem of falling out of the mine cart.
Pressing the space bar on your keyboard now pauses and un-pauses the experience. Shooting the "Mine Ride" level selection board in the main menu room now starts you in the first mine cart ride. We are still looking into the "flashing to Vive world" issues and hope to resolve that in a later update.
Thank You all for your incredible show of support! We are thrilled you like it because we plan on bringing you more VR experiences in the future!