David's mistake ?

I understood it as he was malfunctioning due to a lack of servicing/maintenance. Fassbender has said as much in interviews, so has Ridley.

Maybe he is just showing that he is more human in a way that he can now misrepresent the truth in order to pursue his own agenda. Like a politician for instance.

Walter said the symphony was off, I think this means David was not quite 100% there in the head!

the novelization has a great and detailed chapter on this scene when i remember right

I think his lack of Maintenance could account for it, but also it could be he is struggling to handle the complex Emotions he is now having and also information overload.

Hello everyone. Just joined today. I partially agree with the service/maintenance theory but I would also like to add that as David was able to experience emotions 10 years of isolation may have had an adverse impact on him as well. All he had to focus on were his creations. Would love some feedback. 

@ALYNDRAEL Welcome!! x

Its quite possible that in making this small mistake he is open to making a big mistake that will lead to his downfall in a later film. Much like the scene where he looks at Walters facial wound is an indication for us as to what is going to happen.

I think it is to show that David is in need of some repair/care and that he can make mistakes. So, it's as if his humanity is showing through even more, but since he is an android that means he needs a tune up. 

It also functions a little more specifically to show that David is on a f*%^ed up crusade, here. The book, as BigDave mentioned, goes into that moment a bit further, stretching it and David thinks something along the lines of, "If I got that wrong... made a mistake, what other mistakes have I made this whole time?" He brushes this off as a one-time incident though. It gives room to explore a regretful or I guess confused David in the next film. Now there may be a tiny inkling of doubt in the back of his android head when he is carrying out his experiements 

Like solitary confinement drives people batty. Yeah, there's lots of potential with him it's just so hard to root for him as others have noted. Spaights draft wrote him as a total villain in Prometheus so it's no surprise I guess he's a full blown asshole. Actually Roy batty seems to parallel this idk, was upset he killed jr Sebastian but he did save professor Jones. On the good news though, that Arrival director is gonna make an awesome BladeRunner, I'd almost bet money on it