Continuity mistake: When Henry falls into the pond, the first time, there are several small pylons connected by a chain when the camera is on the walkway. When the camera is in the water, showing Henry as he hits the water, neither the pylons or the chain is visible. There is just an open space where the chair falls over.
Continuity mistake: As Harry goes into the pond the second time the pylons are connected now with yellow crime scene tape when the camera is out over the water looking at Harry on the walkway. As the camera is in the water, watching Harry fall in, the pylons are gone, even though they should be in the shot, and are connected by a wire instead of crime scene tape.