Are Goji Berries Poisonous To Rabbits?

I would not feed these berries to rabbits based on their high sugar content.  Rabbits are hind gut fermenters and do not tolerate sugar well.  Their diet should be composed of mostly fiber.  
The main component of a rabbit's diet should be fresh timothy hay; this should be available at all times.  Also feed a pelleted timothy-based rabbit diet.  Vegetables and treats should be fed sparingly comprising no more than 10% of the diet.  Fresh water should be available at all times.

They are not poisonous but should be fed sparingly.