Yeah, it’s a common household knot that you know about if you do anything around your house.
I’ve seen a photo from last October’s race weekend. I honestly can’t tell what kind of knot it is because the picture is taken so far away. Doesn’t look like a bowline to me. The knotted portion of the rope does look bigger than it would for a bowline. That said, I don’t know why anyone would tie a slip-knot for a rope-pull. That’s just stupid.