Okay I got another one, from another relatively well-researched series (in S1 anyway), which is the hilariously overwrought but fun BBC series (feat. Rose Leslie of Ygritte fame), Vigil.
The first series was set on a nuclear submarine and the nitpicks I had were mostly related to set/SFX, which always seem a little unfair - like, the missile tubes were implied to be vertical and sort of in the middle of the sub - they're actually slanted and to the side - this is the case in most modern ballistic missile subs - and when they had the sub using its foreplanes to go up, they didn't actually animate that, they just showed the same animation from a different angle (the sets were fun though). The sheer amount of intrigue occurring on one nuke boat was implausible but it was fun if trope-y (also appreciated the flashbacks being handled pretty well, though the complex politics of the main mystery were largely both-sided/"what can one man do?"'d). Anyway!
The second series is about some flying military drones with a bizarrely Warhammer 40K vibe (each drone in the "squad" has different primary weapons, which is cool if highly implausible), and they've really tried to lock down a lot of the potential plot holes and narrow the scope of the mystery, and they did a good job. But holy naughty word did they screw up on one thing:
They had multiple characters in our air force refer to our air force as "The British Air Force".
No.
Just no. No-one actually in the actual air force, is going to call it that. That is the most civilian-or-foreigner-ass name possible.
It's the Royal Air Force.
Just like it's the Royal Navy. And I don't say that as a royalist (I'm not), but rather someone completely tangentially involved in the military - I was in the cadets for less than two years (long story), but even I know that. Like, anyone who has ever been in the navy or air force could have told them that - I imagine a lot of American soldiers could have told them that. The army isn't the "Royal Army", it's the British Army, that's different, but even being in that should let them know. They did a lot of other elaborate research but someone managed to mess up this super-basic cultural grounding element. If it was an American show or writer I'd understand, but it's a British show with British writers.