Deliberate mistake: When Cliff crashes into the pond after his first flight, Peevy tells him that he has to look around with his eyes and steer by moving his head. However, just before this as he is flying next to the passenger airplane, he looks over at it, turning his head to the left without changing directions at all.
Deliberate mistake: With the rockets positioned on the rocketeer's back, their thrust would create an unopposed moment about his center of gravity. This would result in the flyer being slammed face first into the ground, not flying straight up. (Note that functional rocket packs, such as were flown briefly in "Thunderball", place rocket nozzles on either side of the flyer's torso, not both on his back.)