My sister let her rabbits free range in her back yard, I've only seen two strange things with them.
The first, is how they sit motionless in the rain. I've also noticed that the wild cottontails near me will do the same thing, but just not as long.
Second, is that the stray cats near my sister's place will just sit in silence with the rabbits. They sit about 1-2 feet apart from one another. Neither cats nor rabbits looked uneasy, they all seem calm.