On March 27, 2001, at 1540 mountain standard time, a Beech 95-B55B (T42A), N38KS, was destroyed by post impact fire following an unintentional landing gear retracted landing at Front Range Airport, Watkins, Colorado. The airline transport certificated flight instructor and his two students were not injured. The flight was operating as an instructional flight under Title 14 CFR Part 91 and no flight plan was filed. Visual meteorological conditions prevailed during the flight which departed Centennial Airport, Englewood, Colorado, at approximately 1440. The flight instructor said he forgot to lower the landing gear. Following the accident, the two student pilots were interviewed by an FAA inspector. They related that the only aircraft problem they were aware of was that the mixtures moved when the throttle setting was adjusted. A subsequent examination of the aircraft revealed that the right throttle landing gear warning lever had rotated 90 degrees and was hung up on the left mixture control. When the right throttle was moved, the left mixture moved with it. The left throttle landing gear warning rod was fixed in its proper position. Due to aircraft damage, it is unknown if this condition affected the operation of the landing gear warning system.