The HR-1's power-off, gear-up slide through the berry patch -- after a cartoonish "flareout" -- lasted eighteen seconds before the camera cut away, the airplane still moving at a good clip, seemingly a constant speed (maybe they were greaseberries?). Plenty of time for Leo to mug for the camera.
Plus he handles the controls like it was a skiploader, rather than a high-performance airplane. Jimmy Stewart, at least, knew how to "fly" an airplane in the movies.
In the interview on the bonus disc, director Scorsese admits that before making this movie he knew nothing about aviation. No kidding.
Howard Hughes was passionate about technical accuracy in his films; he would have hated the aviation scenes in this movie.
-- Pilawt