Actually, the odd mistake or two is quickly forgotten. Far worse is to be considered to be dragging, speeding up or generally not playing the song.
Following on from that, foster a culture where a noticed mistake is cause for a smile between players, not a death stare.One thing that helped me when I'm too self-critical is I think about when other members of the group flub up, I really don't care...
When people started posting those isolated drum/bass/guitar tracks on YT of legendary songs, I sure noticed some blemishes that I didn't before.Put on one of your favourite albums and listen, I mean really listen, closely to each part. I'm willing to bet you dollars to donuts that under intense scrutiny, each and every musician on that album made at least one "mistake" - at least according to them.
Start Me Up...Go listen to some early Rolling Stones recordings. Charlie Watts made mistakes that have been recorded for posterity. Still, he's a great drummer and unless you know where the mistakes are you'd never know the difference.