For me it's seat belts, fire extinguisher location/operation, how to unlock/slide the canopy, and where the Life Hammer is in case we flip in an off-airport landing. (Usually the plexi breaks when you flip, but good to have the tool just in case).
I also tell them that in case I'm incapacitated, hold down the radio's flip/flop button for 5 seconds to call up the emergency frequency...then declare an emergency and get vectors to someplace with long runways like Chino or Ontario.
Hey, they're riding in an Experimental aircraft built in a garage...what did they expect?