During the chase, the left wheel is wrenched off the biplane after D.B. uses it to pierce the roof of a car. But in later scenes, the biplane appears with its right wheel missing.
In the chase scene with the biplane the image is occasionally inverted so that the wrong wheel appears to be missing and the word "Restricted" below the cockpit appears as a mirror image.
During the opening scene, the narrator says, "On Wednesday, November 24, 1971 at 6:27 p.m. aboard flight 305 from Portland to Seattle, the following event actually took place," then it shows D.B. Cooper jumping from the plane. D.B. Cooper did hijack Northwest Orient flight 305 en route from Portland to Seattle on that date as stated, but it then landed at Seattle-Tacoma International Airport and then took off again headed south (no longer as flight 305) and he didn't actually jump until around 8 p.m. More to the point, as shown on screen, it was clearly daylight or perhaps twilight at various points during this scene, but the sun set around 4:30 p.m. in western Washington (where the jump occurred) on November 24, 1971 so it would have been pitch black at 6:27 p.m. and at 8 p.m.