There can be several reasons why a rabbit doe builds a nest but has some of her babies outside of it. Here are a few possible explanations:

1. Nest building behavior: Rabbits have a natural instinct to build nests for their offspring. The doe may create a nest to provide a warm and secure environment for her kits. However, she may not always be successful in confining all the babies within the nest, especially if she has a large litter or if the nest is not well-constructed.

2. Maternal adjustment: Sometimes, the mother rabbit may adjust the location of her kits after giving birth. This can be due to various factors, such as discomfort in the nest, a perceived threat, or a desire to move the kits to a safer or more suitable location. In such cases, she may carry or push some of the kits out of the nest.

3. Health issues or complications: If a mother rabbit is experiencing health problems or complications after giving birth, such as pain, discomfort, or weakness, she may have difficulty properly caring for all her kits. This can result in some of the babies being left outside the nest.

4. Inadequate nest construction: If the mother rabbit's nest is not well-constructed or lacks sufficient bedding material, some of the kits may fall out or wander away from the nest area.

It's important to monitor the situation closely if you notice that some of the babies are outside the nest. Ensure that the environment is safe and warm, and consider providing additional nesting materials or making adjustments to the nest if necessary. If you have concerns about the well-being of the kits or the mother rabbit, it's recommended to seek guidance from a veterinarian or an experienced rabbit breeder who can assess the situation and provide appropriate advice.