So your truck is in the negative zone, wherein all you see are the shadows. Even though, this is the shadow world, that doesn’t mean that you won’t encounter obstacles as they are still there. The problem is that they aren’t easy to be spotted since they blend with their surroundings.
The objective of the game is to get the facility within the set time or if you can do it faster than do so. Don’t worry about flipping over as it is not the end of the game. You can easily get back on track by flipping over again. However, while it may not destroy your truck, it could slow you down.