When Stony and his men capture the men holding Ned and the airplane hostage, Ned is seen sitting in the pilot's seat right next to the open door. There is no other door visible on the left side, and Ned does not have any visible restraints except that his hands are behind his back. All of a sudden, Lullaby walks up to Ned from behind to untie Ned, who now has a rope wrapped twice around his body and is sitting in one of the large reclining seats in the passenger cabin.
From the outside, the passenger area windows are shown as small, tapering windows with white curtains, and the doors are about three feet tall. From the inside, the windows are larger rectangular windows with dark curtains, and the doors are shown to be tall enough to almost be able to step through while standing upright.
The Spartan Executive Model 7W does not have an Emergency Fuel Release Valve as shown and cannot dump fuel while in flight.
The aircraft shown, N17615, is a 1938 Spartan Executive Model 7W. It is a single-engine monoplane with seating for five. During the interior scenes of the aircraft, the cabin is huge, with reclining seating for six, in three rows, plus two pilots up front, and a cabin that one can comfortably stand up in. The actual aircraft cabin is about four feet tall and only has one row of small seats immediately behind the pilot seats. The Interior is easily at least three times larger than the actual aircraft.
When the bandits are chasing the bus at the start of the film, the number of riders keeps changing between four, five, or six.
The Duke refers to the bus as a stagecoach when they start riding to the rescue.
It is 1938 and they are flying one of the most advanced single-engine private aircraft made, yet, except for the Oro Bus Lines bus, no one ever uses a car or truck to chase the criminals or to go anywhere. This is in spite of the fact that all of the chases occur on improved dirt roads that would be more than capable of accepting those vehicles.
Shooting at the robbers from horseback while the bad guys are standing beside it with passengers among them is unreasonably dangerous for the three heroes to do.