This North American B-25 Mitchell bomber was converted into a camera ship for the movie.
Most of its various gun positions now were covered by plexiglass blisters that allowed filming in almost all directions.
(photo via Aircraft Magazine)
The tail of the B-25 was open to allow for easier filming, though it was awful windy for the cameraman.
(FlyPast magazine September 1989)
The only real Junkers Stuka (a Ju-87D) is owned by the RAF, and was
brought in for a possible role in the movie (though it was never used).
(photo from Flight International Magazine, September 11, 1969)
This aircraft was known as a "Proctuka", and was a Percival Proctor trainer that had been heavily modified in order to make it look like a German Stuka dive bomber, including the addition of the cranked wings. Flight characteristics of the Proctukas were not good, though, and their flying footage was not used in the film (models were used for the Stukas instead).
(photo from Flight International Magazine, September 11, 1969)
This JU-52 alias CASA 352-L was from the Spanish Air Force.
It had Spanish-built BMW 132 engines but was otherwise authentic.
(photo from Flight International Magazine, September 11, 1969)