3rd Rock from the Sun
William Shatner (as the Big Head) and John Lithgow (as Dr. Dick Solomon)
Shatner shows up at the house complaining that there was something on the wing of the plane he just arrived on.
Lithgow says, “you saw it too?!”
The humor is they both did the same twilight Zone episode. (Shatner doing the original in 1963, Lithgow in 1983’s Twilight Zone: The Movie)
Called “Nightmare at 20,000 Feet”
Plot summary
Bob Wilson (William Shatner) is a salesman on an airplane for the first time since his nervous breakdown six months ago. He spots a gremlin on the wing of the plane. Every time someone else looks out the window, the gremlin leaps out of view, so nobody believes Bob’s seemingly outlandish claim. Bob realizes that his wife is starting to think he needs to go back to the sanitarium, but also, if nothing is done about the gremlin, it will damage the plane and cause it to crash. Bob steals a sleeping policeman’s revolver, and opens the window marked “Auxiliary Exit” to shoot the gremlin, succeeding despite the fact that he is nearly blown out of the plane himself. Once the plane has landed, although he is whisked away in a straitjacket, there is evidence of his claims: the unusual damage to the plane’s engine nacelle — yet to be discovered by mechanics — that presumably can only be explained as caused by something that clawed at the structure’s airframe.