In the season 3 episode of Black Mirror "Hated in the Nation" the protagonist DCI Karin Parke and her colleague Blue visit a company that creates honeybee-mimicking drone insects known as ADIs. There they talk to Rasmus Sjoberg who "heads swarm" (presumably meaning that he is the boss when it comes to the technical side of the business). While Rasmus explains the ADIs to Karin and Blue he coughs.
Karin: They navigate?
Karin: You don't... I don't know... steer them?
Blue: They're autonomous. [to Rasmus] That's right, isn't it? They make their own decisions. They look after themselves.
Rasmus: Yes. You see, the ADIs cover the whole of the UK. We couldn't command each one individually ourselves. It's just not logistically possible. No. [coughs] We simply set the behaviour and leave them to it. They even construct these hives themselves. They reproduce...
Karin: They reproduce?
I've seen this episode countless times and the cough seems so intentional, especially after watching it that many times. I guess if the actor just had to cough a scene would be filmed again, so this has to be in the script, but why?
My only guess would be that this puts suspicion on Rasmus, leading the audience (which apparently happens several times in the episode). But I'm not sure how his coughing could be linked to him committing a crime. If he were nervous, surely there would be other signs as well. Also, in this and the following scene, it seems like the most suspicious character is Blue. In her case, several hints are dropped and they are way more obvious. It seems unlikely to put suspicion on two characters at the same time but with a different emphasis.
Or maybe it's just that I watched the episode so often that I just focus too much on the coughing, knowing that it somehow bugs me and thus noticing it even more.