Just saw the film and before Brando shoots Richard Boone, Boone signals with his flashlight and there seems to be signal back from the house. The only person in the house was a tied up Pamela Franklin. Who signaled from the house?
shareActually Richard Boone is signaling to a boat at sea and the boat signals back.
shareI think you have your perspectives confused. The scene which you're describing is from Marlon Brando's perspective which sees Boone signalling from the house to the boat. Also, we are tricked into not knowing where exactly Brando is, at times he seems close to Boone and other times they seem far apart, so I think the confusion was probably intentional as to disorient the viewer so that Brando's final move would close the film as beautifully as it does.
Final answers: Boone is signalling and Brando sees it, but it is purposely confusing to disorient the viewer into not being sure of how close or far apart Boone and Brando are.