Dodgyoldfart.
You are probably right. All I can say is it looked like the Hawk T1A sight (which I know was of Spitfire vintage).
I will defer to your greater knowledge.
My more general point is that we should not let knowledge ruin our enjoyment of films. The term I always bear in mind is 'suspension of disbelief'.
When I was 12 I saw Top Gun and fell in love with fighter jets. If I'd let the technical inaccuracies distract me I never would have ended up where I am now. Drunk in Texas, but you know what I mean!
I maintain that it was a great film and if it helps a new generation (or new demographic) understand an oft forgotten event then all I can say is well done.
BV