The first officer was flying the aircraft during the final approach. The aircraft's altitude and airspeed were high, but were within company limits. The rain was now heavy enough that the runway lights were visible only intermittently after each windscreen wiper stroke. Just before touchdown the captain, concerned about the long touchdown point (over 3000 feet past the runway threshold) and unable to see the end of the runway, ordered the first officer to perform a "go-around" and the first officer advanced the throttles but did not engage the takeoff/go-around switch (TO/GA). At this point, visibility improved markedly and the landing gear contacted the runway, although the aircraft continued to accelerate. The captain then decided to cancel the go-around by retarding the thrust levers, even though he was not flying the aircraft. This caused confusion as he did not announce his actions to the first officer who still had formal control. When over-riding the first officer's actions, the captain inadvertently left one engine at TO/GA power and as a result cancelled the preselected auto-brake settings.