Jonathan Winters has to be one of the funniest people who ever lived. Even Robin Williams just stares in silent awe when the two of them are together. Remember Winters as "Maudie Frickert," the little old lady he did on, I think, Laugh-In?
The famous movie stunt pilot Frank Tallman actually flew that Beechcraft 18 through the highway billboard in "Mad World." They put the cockpit of a smaller BT-13 WW2 trainer inside the Beech 18's cockpit for impact protection. Then they built the billboard so it would collapse more easily when the Twin Beech hit it. Tallman said afterwards that it felt like he'd flown through a house, as the Beech's windshield and all of the sign debris exploded into the cockpit on impact! Frank Tallman was something else. I should get "Mad World" on DVD--it really is one of those must-have movies.