1. The two "north" running side rails have a staggered cut.
2. The base of the channel is slanted causing the fluid to run along one side.
3. The fluid does a weird movement entering the third turn, with some flowing backward.
4. The height of the two towards is part of the effect.
Actually, look at the three legs up front by the spinning wheel. Look on pause or freeze frame. You'll see some funny business by examining the bottom leg closest to the viewer on the right then going up to the next 'level.' These do not connect.
The only little problem with this, IMHO, is that the water wheel spins faster than it ought to with that little water pouring over it. But damnit! Otherwise I can't see a single flaw in this whole thing. It looks so fucking good!