Revealing mistake: When the tail breaks off of the "German" machine and it careens around the field, you can see the little steerable tail wheel used to control the plane in those scenes. In all other scenes this plane has a tail skid.
Those Magnificent Men in Their Flying Machines (1965)
1 revealing mistake - chronological order
Directed by: Ken Annakin
Starring: James Fox, Sarah Miles, Stuart Whitman, Alberto Sordi
Factual error: Terry-Thomas's plane gets stuck between the carriages of a Paris-bound train (in fact filmed on the single-line track between Bedford and Hitchin). Just before the train plus plane goes into a tunnel you can see the cooling towers of Bedford's Goldington Power Station (circa 1960) behind TT's head. (01:58:20)
Count Emilio Ponticelli: Like-a Caesar, we go to England.
Trivia: The sequence where the aeroplane lands on a train was shot on the Bedford-Hitchin railway line, which was closed in 1964.