Visible crew/equipment: Steed is seen driving along with Purdey and Gambit in rural France. The camera was probably mounted on the front passenger side door, pointing in. As they near their destination, the camera pans to reveal a farm house, and as it pans, a professional-looking microphone can be seen sitting on the dashboard.
Continuity mistake: Near the end of the show, the squadron has to land on a carrier deck. The shots from the sky go back and forth between a straight deck carrier and an angled carrier deck. Also, an angled carrier wasn't put into use until the early 50's by the British, Black Sheep takes place in WWII.
Revealing mistake: The opening scene was shot twice, complete with a rear-end automobile collision in the foreground for both takes. The initial collision destroyed the taillights of the first car and the headlights of the second car and ruptured the second car's radiator on impact, spilling its contents into the street. The production crew attempted to sweep away the debris with a broom before the scene was reshot. If you examine the roadway before the two cars appear in this scene, you will see a prominent splatter on the pavement that has been swept with a broom almost precisely where the cars impact again moments later.