For me, it would be the scene in The Chase where Lorna (Michele Morgan) is murdered in the Havana night club in front of Chuck (Robert Cummings). In fact, a great deal of The Chase is surreal, maybe because most of it is a malarial fever dream. Some think it's a mess but I like it more every time I see it. In fact, just the conversations between Peter Lorre and Steve Cochran, playing the two extremely sadistic antagonists, are surreal in the extreme.