I need to know that there was some deeper meaning in this movie. You don't make a movie like this without it. And if you don't, then it's a waste of time. Here is my take with spoilers.:
Dolf is dead and can't let go of his life. He was the one driving the van with his dog in it. It's raining at work because his job is the tether of his life. The rain is actually the firemen putting out the fire in the van. His firing is actually his death but he can't let go so he keeps coming back because he is not ready to accept the fact that he died. His dog is also part of that denial.