I knew how deus ex machina was used in movies, but I didn't necessarily think it would be used in this movie. The movie was about the AI, so of course, I just assumed that was the reason for the title.

In the context of the movie, I feel like the deus ex machine moment was when Ava turned Kyoko on Isaac's character. She had never displayed that ability, but I guess she never had opportunity prior to that.

Other movies have shown that creating hyper advanced AI will backfire more times than not, but I've never seen one manipulate a character or an audience, the way Ava did.