When I was gigging with a band, we used to quite often miss entire verses. We got good at it though, me and the drummer could pick up pretty quickly when the singer/guitarist went to the wrong section. We all missed notes or played the wrong part occasionally. No one in the audience ever notices. It's all good.
I've seen some of the biggest rock and metal bands in the world completely screw up songs and have to start again. They make a joke about it, make fun of the person who messed up and its all fine.
Perfection is boring anyway