That’s true, but this reminds me of something similar that actually happened to me. I was watching Mira Nair‘s version of Vanity Fair, in which there is a scene where there are Indian musicians playing at a party. When I saw them, a voice screamed in my head “Sarods didn’t have metal fingerboards in the 19th century!”, followed immediately by a soft voice saying “nobody but you is going to notice that”. Of course, a lot more people will be aware of your example than mine, but I think the difference is only one of degree. It’s also not impossible that the person might have really said that, if she was basing it on her own experience rather than the expert opinion of the time. The point is that historical dramas often shade the truth for dramatic effect, and all historical claims in them should be checked before being accepted as truth.