Ummm, so why is this a nit? I don't recall, but did they say they weren't the first men in flight or something when they actually should have been, or what?
have you noticed in the movie that there are some other things that don't match up with history? I've never heard of a giant machine spider in history either. So this is obviously another thing that the creators disregarded history for the sack of the story line. Also I thought I'd mention this: You said Artie and Gordon....There's Artemis Gordon and Jim West. You said the same person, both names! (Slip-up on you)
This movie was not, in any way, shape, or form based on accurate history. There were no Black Army officers, let alone "top operatives" with direct connections to the President. There were no rocket-powered bicycles, giant mechanical spiders, super electromagnets, fully functioning tanks, etc. The movie is obviously not meant to be historically accurate. As such, I do not believe historical inaccuracies are slip ups.