How A.I. Mistakes Can Have Real-life Impacts

The new world powered by Artificial Intelligence is all around us nowadays. From Alexa to self-driving cars to smart homes, AI is changing the way in which we interact with this world. A lot of people ( and some guy called Elon Musk) have also mentioned quite a bit about the dangers of AI and how it can lead to humanity as we know it. Can an AI make mistakes? And how serious can these mistakes be?