Chasing a Rabbit with my Labrador Retriever

I am hiking upward on a trail through a forest with my white Labrador Retriever. We arrive near a large rock and scramble over it to reach the other side. On the other side, my white Labrador Retriever and I are now in a large open field of tall grass. We spot a small rabbit, so my dog barks and starts chasing it through the field. I chase after them through the grass, trying to keep up with their incredible speed. Suddenly, it is quiet, and I am no longer in a field but in what seems like a desert. I continue walking, but there is nothing for as far as I can see except for white sand. A small door appears in the distance, so I start walking toward it. I see that it is closing but I can't seem to get closer no matter how fast I run toward it.