"From Hell to Victory", starring the incomparable George Peppard. If there's a category for "So bad it's good", this would be the winner. You name it, it's got it, but very badly. A must-see for all aviation type persons.
With Spitfires in German markings and Spanish Me-109 clones in RAF 'desert cammo' during the Battle of Britain, its got to win this one for worst film hands down.