The gear with integrated hour hand wouldn't be able to rotate in the space that it's mounted. In order to tell the time against the ring, the hand would need to be much further away from the gear.

Secondly, the funnel bit seems to have no real purpose; if you have to pipe water to the funnel, why not just bring it directly to the cup at the bottom? In real water clocks there is usually a primary collector but it's built in such a way that it overflows at a certain level so that the pressure on the outgoing line stays constant. The funnel here does essentially nothing and there is nothing else in the clock that would provide any kind of flow rate calibration; you'd have to do that externally.

Lastly, it's not clear how you'd reset the clock. Can the collector be removed separately or do you need to turn the whole clock upside down to pour the water out and get the float back down to the bottom?