During a ferry flight, while turning from downwind leg to base leg of the airport traffic pattern, the pilot became distracted when the cabin door popped open. The pilot continued on the approach and prior to touchdown, advanced the propeller rpm, set the mixture to full rich, and put the flaps down. As he reduced the throttle he heard a horn and thought it was the stall warning horn, but afterwards believed it probably was the gear warning horn, as they sounded somewhat similar. He did not think anything about it as he normally hears the stall horn at touchdown. He stated that he felt like the approach was a little faster than normal and he reduced the power to help to try to slow down. At touchdown he realized that he had not selected gear down. The airplane landed on its belly and when it came to a stop, there was smoke in the cockpit. Then when the pilot exited the cabin and stepped out on the wing to exit the airplane, he noticed flames on the aft side of the right wing. The airplane was subsequently destroyed by a postcrash fire.