You think fast and spin the answer in a positive light. If they ask you about mission statement and you don't know, just be honest and say you don't know.
This other girl in the lobby told us that they asked her about the mission statement, and I was still waiting to be interviewed. She said she knew it and told us it was "serving the underserved," so I said that when I was asked. I thought I nailed that interview, so I looked up the mission statement afterwards and it was completely off.
I played myself. Waitlisted.