Other mistake: When the Disco Volante separates to escape the cruisers firing on it, the "cocoon" is seen facing the pursuing ships stern first. When the shot changes to show the gunners firing on the ships the back half of the "cocoon" has turned completely around; the gunners are firing from the separated mid section of the Volante and the stern of the "cocoon" is now facing away from the cruisers, making it easy to see which parts of the scene were filmed live and which were done in the studio.demodon
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)
Revealing mistake: In the opening sequence when Colonel Ryan's plane has crashed and is on fire, you can see a metal pole supporting a burning aircraft shell, not a real plane.
Factual error: Before the damaged plane is dismantled, in some shots the three propeller blades of the port side engine are a mixture of clockwise and anticlockwise type. (The twist along the length of the blade goes the opposite direction depending on the type).