Yes: you can (for example) confuse a vision algorithm into thinking an image of a turtle is a rifle https://mashable.com/2017/11/02/mit-researchers-fool-google-...

Yeah, many ways. Besides what the article describes there are at least 5-10 known attacks at the moment.

By “attack” the authors mean figuring out ways to trick the network into classifying things incorrectly. For example, you might attack a network that recognizes faces by determining certain inputs that still are recognizable as faces to a human, but not to the network.