Homer Simpson in 'Kidney Trouble' - S10-E8
Corrected entry: This concerns when Bart is in the ghost town, watching the robotic can-can dancers. When the four dancers first come out and start their kicks, one loses a leg which goes flying out of the window, breaking it. However when the camera cuts back to the dancers they all have both their legs.
Correction: No, there is always a leg missing and none of the other parts reappear.
Matty W