Yes - the bucket drop is true - How Nate figured out to do it was while he was in flight school. He was daydreaming during class and was dangling a pencil on the end of a string. As he turned his hand in a circle the pencil would tunr around underneath. He found that at a certain length of string and radius of circle and speed of turn that the pencil would stand still at the end. This he practiced in a Cub in flight training. He had a passenger using a reel of rope with a bucket on the end. This "bucket drop" and other mission manuevers such as package dropping and picking up were a common practice lesson in the Moody flight training. These manuevers are not practiced much anymore with the faster airplanes. I was not taught this at Moody Aviation when I attended but then we did not fly Cubs either. This manuever is shown in the movie. Steve Saint (Nate Saints son) does all the flying of the PA14 in the movie and practiced these manuevers just for the film. Nate had many interesting things he developed. An Auxiliary fuel system that bypassed the carb, a sling setup under the PA14 that allowed his to carry sheets of galvanized roofing, and many other "mods". There is a lot to learn from Nate Saint - he really was a pioneer.
Thanks- Bill